PHYSIOLOGY PRACTICAL GM 2022 2 ЧАСТЬ

FEDERAL STATE BUDGETARY EDUCATIONAL INSTITUTION OF
HIGHER EDUCATION
«BASHKIR STATE MEDICAL UNIVERSITY»
OF THE MINISTRY OF HEALTHCARE OF RUSSIA
DEPARTMENT OF NORMAL PHYSIOLOGY
PHYSIOLOGY PRACTICAL
Education Guidance for Students of General Medicine Faculty
Part II
Physiology of Special Functions of CNS, Respiration, Digestive System,
Metabolism and Nutrition, High Nervous Activity and Special Senses.
A.F. Kayumova, O.S. Kiseleva, K.R. Ziyakaeva, I.R.Gabdulkhakova
UFA 2022
УДК 612.8
ББК 28.903я73
G 36
Printed by the decision of“Federal State Budgetary Educational Institution of
Higher Education BSMU” (document № ______
2021)
Normal physiology. Part II. Physiology of special functions of CNS,
respiration, digestive system, metabolism and nutrition, high nervous activity and
special senses.: education guidance for students of General Medicine faculty
/A.F.Kayumova, O.S. Kiseleva, K.R. Ziyakaeva., I.R. Gabdulkhakova- Ufa: BSMU,
2022. pages.
The Physiology practical was compiled on the basis of the work program (2021), the
current curriculum (2021) and in accordance with the requirements of the Federal State
Educational Standard of Higher Education 3 ++, in the specialty 31.05.01.–General
Medicine. It presents the physiology of special functions of CNS, respiration, digestive
system, metabolism and nutrition, high nervous activity and special senses. The manual
contains the techniques and theory necessary for the study of students of the faculty of
General Medicine.
Illustrations are taken from open Internet resources.
Recommended for publication by the Coordination Scientific and Methodological
Council and approved by the decision of the Editorial and Publishing Council of the
FSBEI HE BSMU of the Ministry of Health of Russia work.
For English speaking students of General Medicine faculty.
УДК 612.8
ББК 28.903я73
G 36
© Kayumova A.F., Kiseleva O.S.,
Ziyakaeva K.R,Gabdulkhakova I.R.
© BashkirState Medical University, 2022
2
CONTENTS
THEME 1. Special Physiology of Central Nervous System (CNS)……………1
Lesson 1. Role of Different CNS Parts in the Regulation of Movements
and Muscle Tone.…………………………………………………………………5
Exercise 1.Positional-tonic Reflexes in Guinea Pig. ………………………….…15
Exercise 2.Straightening reflexes in Guinea Pig. ……………………………....15
Exercise 3. “Lifting” and ”Landing” Reflexes in Guinea Pig ……………..……16
Lesson 2.Physiology of Vegetative Nervous System. Investigation
of Some Human Vegetative Reflexes.…………………………………………….17
Exercise1. Investigation of Vegetative Tone by Index Kerdo.………………..24
Exercise 2.Investigation of Vegetative Tone by Questionnaire
Design Method.……………………………………………………………………24
Exercise 3.Investigation of Vegetative Reactance by Extracardial
Reflexes.…………………………………………………………………………...26
Exercise 4. Analysis of Vegetative Reactance by Cold Test. ………….………..27
Exercise 5. Other Vegetative Tests.………………………………………………28
THEME2. Physiology of Respiration.…………………………………………....29
Lesson 1.External respiration. Gas Exchange. Research of Parameters
of External Respiration. Control of Respiration …………………………………..29
Exercise 1.Spirometry. …………………………………………………………….40
Exercise 2.Lung Volumes and Capacities. Spirography. ……………………….....42
Exercise 3. Pneumography………………..………………………………………..43
THEME3. Digestive System. …………………………………………….………46
Lesson 1. Digestion in Oral Cavity and Stomach. ………………………….…….46
Exercise 1. Influence of Saliva on Starch. ………………………………….……54
Exercise 2. Determination of Mucin in Saliva. …………………………….……55
Exercise 3. Influence of Gastric Juice on Milk. …………………………….....…56
Lesson 2. Digestive System. Digestion in Intestine. Role of Bile in Digestion…....57
Exercise 1. Role of Bile in Digestion……………………………………….…....63
Exercise 2. Identification Test on Bile Pigments and Bile Salts. ……………...…64
Exercise 3. Gmelin’s Test on Bile Pigments. ………………………………..…..65
THEME4. Metabolism and Nutrition.…………………………………...………..66
Exercise 1. Methods for Determination of Energy Output.……………..………….69
Exercise 2.The Basal Metabolism Calculation by Garris - Benedict’s Tables……74
Exercise3. Determination of Energy Output by Reed’s Nomogram and Hemodynamic
index.…..…………………………………………………………….74
Exercise 4. Analysis of Energy Value of Daily Student’s Diet.…………………....77
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Exercise 5.Composing of the proper food diet with calculation of rational nourishment
principals..……………………………………………………………77
THEME 5: Highest Nervous Activity. ......................................................................82
Lesson 1. Methods of Investigation of Cerebral Hemispheres. Cortex Functions.
Investigation of Active Bioelectrical Processes in Brain. Functional Asymmetry of
Hemispheres Performing Sensor and Motor functions.…………………………….82
Exercise 1. Determination of Individual Profile of Functional Asymmetry……..88
Lesson 2. Conditioned Reflexes. Conditioned Inhibitory Reflexes
Methods of Making Reflexes and Methods of Formation of Conditioned Inhibitory
Reflexes. ……………………………………………………………………………91
Exercise 1. Making of Defensive Conditioned Reflex on Human. ……………….95
Exercise 2. Making the Conditioned Wink Reflex on Human. ………………….95
Lesson 3. Spatiality of Human Mental Activity. Types of Highest Nervous Activity.
Analytical-synthesis Functions of Cerebral Cortex. ………………………………..94
THEME 6. Sensory System…….. ………………………………………………..100
Lesson 1. The Special Senses. Physiology of Visual System.……………………100
Exercise 1. Determination of Visual Acuity by Using Rot’s Apparatus
and Sivcev’s Table. ………………………………………………………..104
Exercise 2. Determination of Visual Fields. ………………………………107
Lesson 2. The Sense of Hearing. ………………………………………………....109
Exercise 1. Determination of Auditory Acuity……………………………111
Exercise 2. Determination of Bone and Air Conductivity of Sound. ….....113
Exercise 3. …………………………………………………………………113
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THEME 1.SPECIAL PHYSILOGY OF CENTRAL NERVOUS SYSTEM
Lesson 1.Role of different CNS parts in the regulation of movements and muscle
tone.
Questions for studying.
1. Organization of the spinal cord in motor functions. Role of the muscle spindles in
motor control. The descending and ascending spinal cord tracts.
2. Medulla oblongata. The nuclei of the cranial nerves. The vital centers: the vasomotor
center, the cardiac control center and the respiratory center. Midbrain. Functions of
the cerebral peduncles, the red nucleus and the substantianigra. Static and
statokinetic reflexes.
3. The reticular formation. Reticular activating system. Excitatory and inhibitory
function of thereticular formation.
4. Thalamus. The generalized thalamocortical system: role of sensory information on
cortical activity. Function of the thalamus in attention and in mechanisms of pain.
5. Physiologic anatomy of the basal ganglia. Motor functions of the basal ganglia.
Function of the different basal ganglia. Clinical syndromes resulting from damage
of the basal ganglia.
6. The cerebellum and its motor functions. Functions of the cerebellum in controlling
movements. Clinical abnormalities of the cerebellum
The spinal cord consists of 31-32 segments and 31 pairs of spinal nerves. It is
symmetrically divided into two lateral halves. The spinal cord contains motor nuclei
(motoneurons) in anterior horn and intermedial (inserted) nuclei in posterior horn.
Lateral horn cells are autonomic (intermediolateral) cell group.
Each segment of the spinal cord includes posterior - sensory and anterior - motor
roots. The anterior roots consist of efferent fibers of motor neurons and preganglionic
autonomic neurons (fig.1).
5
Figure 1.The spinal roots.
Functions of spinal cord:
1.Conductive function. The spinal cord consists of the main conductive parts to the
higher centers of the spinal cord and brain and back.
The ascending pathways:
- transfer information from muscular, tendinous receptors and tactile receptors of
skin;are formed by axons of spinal ganglion, and send information to cerebral
cortex and cerebellum.
The descending pathways:
- Pyramidal: cortical-spinal tract. It originates from the neurons of the motor areas
of the cortex and ends on the motor neurons of the spinal cord. This is a conscious
regulation of motor activity.
- Extrapyramidal pathways: rubro-spinal, tegmental-spinal, reticulo-spinal,
vestibulospinal, olivospinal (fig.2).
6
Figure 2.The spinal pathways.
2. Reflex function - the spinal cord is the main center of the reflex action of the trunk
and limbs.
Classification of spinal reflexes
I. Somaticreflex
1. Tone reflex
(myotatic reflex)
2. Phasic reflex
(flexor reflex,
II. Vegetative reflex
1. vasomotor reflex
2. urinary reflex
3. defecation reflex
4. sexual reflex ect.,
crossed extensor reflex)
Spinal vegetative reflexes are important to control activity of viscera.Reflex arcs of
skin-visceral reflexes have a segmental structure. These reflexes begin with skin
receptors and end with a change in the functioning of internal organs. The essence of
this structure is that each segment of the spinal cord innervates the corresponding
metamere of the body (fig. 3). The therapeutic effect of acupressure, acupuncture, local
warming and cooling is based on the segmental principle of skin-visceral reflexes. The
intersegmental principle of spinal reflexes is that each metamere of the body receives
innervation not only from the segment, but also from the overlying and underlying
segments.
Spinal somatic reflexes are important to motor activity and regulation muscle tone and
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posture.
Figure 3.The segment of spinal cord.
Myotatic or stretch reflex.
Muscle tone is purely a reflex process.Thus muscle tone is maintained by impulse
activity of afferent nerves whose endings lie in the muscle spindles.
Muscle spindle is an organ, which lies between regular or extrafusal muscle fibres and
richly innervated both by sensory and motor axons. Muscle spindle is composed of a
bundle of modified muscle fibres, called intrafusal muscle fibres. Intrafusal muscle
fibers are divided into 2 groups: nuclear bag and nuclear chain fibers.Proprioreceptors
are found inside the nuclear bag - these are stretch receptors. They are excited when the
nuclear bag or nuclear chain is stretched. Impulses from them are sent to the spinal cord
to the alpha motor neurons of the anterior horns, which innervate the extrafusal muscle
fibers (fig. 4).
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Figure 4.The myotatic reflex. Extra- and intrafusal fibers.
When the muscle tone decreases, its muscle lengthens and the greater the stretching
of the proprioreceptors of the intrafusal fibers and, consequently, the impulses to the
motor neurons of the anterior horns of the spinal cord. This means that more stimuli go
to the muscles and their tone increases. This is the principle of operation of the gamma
loop, which regulates muscle tone (fig. 5).
9
Figure 5.The myotatic reflex or gamma loop.
The tone of the skeletal muscles is established at the level of the spinal cord, but it is
regulated (increased or decreased) due to the descending influences of the overlying
centers (tab. 1).
Table 1.
Influence of supraspinal centers on the muscle tone.
CorticoRubroReticuloReticulospinal
spinal tract
spinal
spinal
(pyramidal)
medial
lateral
tract
(from pons)
tract
(from
medulla)
Alfa, gamma
motoneurons of
flexors
Alfa, gamma
motoneurons of
extensors
Vestibulospinal
lateral
tract
+
+
-
+
-
-
-
+
-
+
Myotatic or stretch reflex:
1.makes the movement smooth and accurate
2. maintains the line of gravity constant (equilibrium).
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The posture is not the active movement itself (which in most cases is a voluntary
process) but is the associated redistribution of tone in the different groups of related
muscles.
Brainstem
includes medulla oblongata, pons, midbrain. Brainstem has refectory and conduction
functions. All cranial nerves exceptI and II pairs are based in the brainstem (tab. 2).
Table 2.
Number
of the
nerve
III
Name of cranial
nerve
Cranial nerves
Includes fibers
Efferent
(motor and vegetative)
Efferent
V
Oculomotor
nerve
Nervous
trochlearis
Trigeminal nerve
VI
Adducent nerve
Efferent
VII
Facial nerve
Efferent
(motor and vegetative)
VIII
Vestibulocochlear nerve
Glossopharyngeal
nerve
Afferent
IV
IX
Afferent and efferent
Afferent and efferent
(motor and vegetative)
X
Nervous Vagus
Afferent and efferent
(motor and vegetative)
XI
Accessories
nerve
Efferent
(motor)
XII
Hypoglossal
nerve
Efferent
(motor)
Functions
Accommodation, movement
of eyes
The movement of eye
muscle
Chewing and sensitivity of
the person
Movement of eyes
The movement of mimic
face muscles, salivation and
tears. Flavoring sensitivity
of tongue
Hearing, sense of
equilibrium
Flavoring sensitivity of
tongue, sky. Salivation,
swallowing
Signals from internals,
regulation of inhibitions of
smooth muscle, secretion the
exocrine of glands
Movement of the head,
neck, shoulders. Information
transfer from neck muscles
Movement of tongue.
Information from tongue
muscles
Thedescending ways from brain to a spinal cord pass through a midbrain, pons and
medulla oblongata. All ascending pathways which bring sensory information from
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proprio- receptors of muscles, tactile, temperature receptors and receptors of pain also
pass through brainstem to cerebellum and cerebral cortex.
Reflex function of brainstem.
A lot of vital reflexes are based in the level of medulla and pons. They are: respiratory
and vascular-motor centers. Reflexes of salivation and swallowing, vomiting and
sneezing, coughing, lachrymal and blinking locate here.
Midbrain as well as medulla oblongata and pons relate to stem structures (fig.6). Primary
visual area and primary auditory area a quadrigeminal (superior and inferior colliculus);
red nucleus, substantianigra, nuclei of nerves reticular formation are parts of the
midbrain.
Figure 6.The brainstem (medulla oblongata, pons and midbrain).
Primary visual area regulates orientative visual reflexes. The animal without cerebral
cortex turns its head and changes pupillary width to light. Primary auditory area
regulates orientative auditory reflexes. Primary visual and primary auditory areas
regulate protect reflex. It arises at sudden action of non-identified incentive and includes
change of a tone of skeletal muscles. A red nucleus activates motor-neurons of flexor.
The condition of a decerebrate rigidity arises at a section of a rubrospinal tract. At
the same time, the tone of the extensor muscles sharply increases. The limbs of the
animal are strongly elongated, the head is thrown back, the tail is raised.It’s happens
12
after cutting the midbrain in experiment between superior and inferior colliculi. The red
nucleus is cut off. The result is: activation of vestibular lateral nucleus which was
inhibited by red nucleus before cut (fig. 7).
Figure 7.The decerebrate rigidity
The substantianigra is a collection of nerve cells containing the pigment melanin. The
black substance regulates the acts of chewing and swallowing, precise movements of
the fingers. Neurons of the substantia nigra synthesize the neurotransmitter dopamine.
This neurotransmitter travels along the axons to the basal ganglia.
Cerebellum and its functions.
The cerebellum is the highest subcortexcentre coordinating motive, vegetative and
behavioral reactions. The functional structures of the cerebellum:the ancient cerebellum
consists of a flocculus, nodule and the bottom of a vermis(fig. 8). It has an entrance
from vestibular nuclei. The old cerebellum consists of parafloccular section and superior
of vermis. It has afferent entrances from a spinal cord. The neocerebellum consists of
hemispheres. It receives afferent entrances from cerebral cortex and from muscle
receptor through the inferior olive. Corpus medullare contains three pairs of nuclei (a
fastigii, dentate and intermediate). It is the main efferent exit of the cerebellum to the
motor centers of the brain.
Functions of the cerebellum:
- Muscle tone and equilibrium regulation;
- Pose and targeted movement coordination;
- Targeted movement programming.
The cerebellum has activating and inactivating impacts on the vegetative centers
(breath, digestive) and activity of internals.
13
Figure 8.The Cerebellum.
Tonic reflexes of a brainstem arereactions aimed at maintaining a normal body position in space. They are divided
into two big groups: static and stato-kinetic reflexes.
Static reflexes are the reflexes of posture (positional-tonic) and straightening reflexes.
Positional-tonic reflexes occur as a result of changes of head position in relation to the
trunk. Under these conditions as the body gravity center is shifted there is a danger of
balance disturbance. In this case the receptors of otolithic body of the vestibular
apparatus, proprioceptors of muscles and tendons and skin receptors of neck are
stimulated. Stimulation reaches the nuclei of back brain (medulla oblongata and pons
Varolii) and the midbrain taking part in redistribution of neck muscles, trunk and limbs
and providing the support of the part of a body in the direction of gravity center shift
(fig. 9).
14
Figure 9. Posture reflexes: changing head position affects muscle tone.
Straightening reflexes - occur as a result of head turnings and body inclinations. They
are directed to the returning a normal position. They represent series of tonic reflexes
started by irritation of otolithic body of the vestibular apparatus and skin receptors of a
trunk, leading to redistribution of neck muscles and returning to the normal position of
a head. Turning of a head is followed by overwinding of neck muscles and tendons that
causes their proprioceptors irritation. It gives rise to a new part of a straightening reflex
providing consecutive redistribution of muscles tone of the forepart and then the back
part of a trunk that leads to the returning to a normal position.
Statokinetic reflexes, - depending on the character of movements, are subdivided into
the reflexes occurring under influence of linear and angular accelerations. The first ones
are reflexes of descent and rise ("lifting"), and also reflexes of "landing". These reflexes
result from irritation of otolithic receptors of the vestibular apparatus, and partially of
semicircular canals. In the beginning of rise under the action of positive acceleration
there comes involuntary bending of limbs, lowering of a head and a trunk. In the end of
rise under action of negative acceleration extension of limbs occurs, thus raising a head
and a trunk. When descending, the given reactions occur in the reverse sequence.
The reflex of “landing” occurs during an unsupported phase of a vertical jump. In the
air animal’s limbs become straighten and move forward. Falling down, the animal
springs its limbs to protect its head and trunk from impacts against the ground.
Statokinetic reflexes occurring under the influence of angular accelerations (rotations
of a body in various planes), develop owing to irritation of semicircular canals receptors
and are directed on returning of a body and its parts to a normal position.
The example of statokinetic reflexes is the vestibular nystagmus representing movement
of eyes in the direction opposite to the direction of rotation. The study of the vestibular
nystagmus is of great importance for the characteristic of the vestibular apparatus in
clinical picture.
15
Exercise 1.Positional-tonic reflexes in the guinea pig.
Purposes:
- to study the static and stato-kinetic reflexes in the guinea pig;
- to study the positional-tonic reflexes in the guinea pig;
- to study the straightening reflexes in the guinea pig;
- to study the “lifting” reflexes in the guinea pig;
Procedure.
The guinea pig is placed on a napkin and its natural position is studied (fig. 10,
a).The animal is taken by its snout, its head is lifted upwards (fig. 10, b). It is marked
that in these conditions forelegs of an animal are straighten, while back legs remain
bent.
Figure 10.The extension of forelegs with lifting of the head.
Exercise2. Straightening reflexes in the guinea pig:
a) The animal is lifted upwards by the shoulder girdle and by the head, then the
trunk is turned by 180 degrees and the head is directed downwards. When the head is
released - it is returned to the normal position, i.e. the crown of the head is directed
upwards (fig.11 a).
16
Figure 11.Returning the head to the natural position after turning the trunk by 180 degrees
a-the head is fixed, b- the head is released.
Returning the natural position after turning the trunk by 90 degrees.
c- the trunk is transferred to the horizontal position, the head and trunk is fixed by the hand,
d- the head is released, it is returned to the normal position
e- the trunk is released, it is returned to the normal position
b) When taking the guinea pig by the pelvis, its trunk is transferred to the vertical
position with the head downwards. It is marked that in these conditions the head of the
animal keeps normal position - is focused upwards(fig.11 b).
c) When trying to lay the animal on its side (by 90 degrees), the posture is restored in
two stages: placing the head with the top of the head up and then straightening the
body(fig.11 c, d, e).
Exercise 3. “Lifting reflexes” and the reflex of “landing” in the guinea pig.
a) The guinea pig is placed on a plate and its position is studied - its forelegs and back
legs are bent, the head is raised. (fig. 12, a). The platform with the animal is quickly
17
moved upwards and downwards. It is observed that in the beginning of the fast
descending its forelegs and back legs are straightened, the trunk and the head are lifted
up (fig. 12, b). At the moment of a sudden stop, in the end of descending, the legs are
bent; the head and the trunk are pressed to the supporting plane (fig. 12, c). When lifting,
reflex reactions change in the reverse sequence.
Figure 12.Change the position of the guinea pig during the fast descending:
a - the initial position
b - the position of the guinea pig at the beginning of the fast descending
c - the position of the guinea pig at the moment of sudden stop
b) The guinea pig is lifted up by the pelvis and by the shoulder girdle; - its legs are halfbent and are hung down. The animal is quickly moved to the ground. It is marked that
during the movement its forelegs and back legs are unbent and straightened forward; its
fingers are fan-shaped.
Observations, results and conclusion.
Lesson 2. Physiology of vegetative nervous system. Investigation of some human
vegetative reflexes.
Questions for studying.
1. Physiology of vegetative nervous system. Structural and functional properties of
somatic and vegetative nervous system.
2. Properties of reflex arch of somatic and vegetative nervous system.
3. Sympathetic and parasympathetic divisions of vegetative nervous system.
4. Adrenergic and cholinergic structures of vegetative nervous system.
18
5. Synergism
and
relative
antagonism
ofinfluenceofsympatheticandparasympatheticdivisionsofvegetativenervoussystem.
6. Vegetative centers. Hypothalamus, its nuclei and their significance in regulation of
vegetative functions.
7. Participation of vegetative nervous system in the fusion of functions.
Purposes:
Investigation
of
reflexes,
characterizing
status
sympatheticandparasympatheticdivisionsofvegetativenervoussystem.
of
Principle. The autonomic nervous system is a motor system concerned with the
regulation of smooth muscle, cardiac muscle, and glands. It is not directly accessible to
voluntary control. Instead, it operates in an automatic fashion on the basis of autonomic
reflexes and central control.
Anatomically, the autonomic outflow is divided into two components: the sympathetic
and parasympathetic divisions of the autonomic nervous system. In the gastrointestinal
tract, these both communicate with the enteric nervous system, and this is sometimes
called a third division of the autonomic nervous system.
Sympathetic preganglionic neurons are located in the intermediolateral (and
intermediomedial) cell columns of the CVIII to LII segments of the spinal cord. Their
axons leave the spinal cord through ventral roots and enter the sympathetic chain through
white communicating rami.
Sympathetic preganglionic neurons synapses are located on postganglionic neurons in
the paravertebral or prevertebral ganglia. Postganglionic axons synapse in target organs.
Parasympathetic preganglionic neurons synapses are located in cranial nerve nuclei and
the sacral preganglionic nucleus. Postganglionic axons synapses are located in target
organs.
The enteric nervous system is in the wall of the gastrointestinal tract in the myenteric
and submucosal plexuses. It coordinates the movements and glandular secretions of the
gut.
The sympathetic and parasympathetic nervous systems regulate the activity of smooth
muscle, cardiac muscle, and glands. These components of the autonomic nervous
system often act in a reciprocal fashion.
Preganglionic sympathetic and parasympathetic neurons release acetylcholine as their
neurotransmitter. This neurotransmitter acts on nicotinic cholinergic receptors (and also
on muscarinic receptors) on postganglionic neurons. Nicotinic receptors are blocked by
curare.
19
Parasympathetic and some sympathetic postganglionic neurons (sudomotor and
vasodilator neurons) also release acetylcholine. The postsynaptic receptors on target
cells in this case are muscarinic and can be blocked by atropine.
Most sympathetic postganglionic neurons release norepinephrine, which acts on α- and
β-adrenergic receptors.
The adrenal medulla receives sympathetic preganglionic input and releases epinephrine
and norepinephrine into the general circulation (fig. 13).
Figure 13. Autonomic nervous system
The autonomic nervous system operates reflexly and in response to descending control
systems, especially the hypothalamus and other parts of the limbic system.
The hypothalamus regulates homeostasis, motivation, and emotional behavior through
control of the autonomic nervous system, endocrine system, and somatic nervous
system. Some of the functions regulated include body temperature, cardiovascular
activity, appetite, water intake, and immune responses.
The hypothalamus controls endocrine function both by the direct release of hormones
in the posterior pituitary gland and by the release of peptides into the portal circulation
of the anterior pituitary gland.
20
The limbic system comprises not only the hypothalamus but also a number of forebrain
structures, including the hippocampus, amygdaloid nuclei, and several nuclei in the
midbrain. Functions of the limbic system include the regulation of aggressive behavior
and sexuality. The hippocampus is involved in the storage of recently acquired
memories and in memory consolidation.
Cholinereceptors.
Acetylcholine cooperates with М-and N-cholinereceptors. They are named so because
possess according to high sensitivity poison of a fly agaric -muscarine or to alkaloid to
the nicotine containing in leaves of tobacco. М-and N-choline receptors basically are
located postsynaptic.
The M-cholinereceptors are localized on membranes of automatically functioning cells
of myocardium, atria- ventricular node, glands of external secretion, innervated by
postganglionic parasympathetic nerves, and also on membranes of cells smooth muscles
of a stomach, uterus, and sweat- glands, innervated by the some postganglionic
sympathetic nerves. 5 variants of M-cholinereceptors are distinguished.
Distinguish also different N-cholinereceptors. Some of the mare localized on
postsynaptic neuron’s membrane of vegetative ganglions, ganglia similar educations
(brain substance of adrenal glands, sleepy glomerule, neurohypophysis), and others are
localized on postsynaptic membranes of fibers of skeletal muscles. There are N-and Mcholinereceptors in CNS.
Besides postsynaptic structures, cholinereceptors are localized in presynaptic
membrane. Stimulation N-cholinereceptors promotes releasing acetylcholine, and
stimulation of M-cholinereceptors inhibit this process.
Adrenoreceptors.
Epinephrine
and
norepinephrine
cooperate
with
adrenoreceptors.
Adrenoreceptors divide into two basic groups –α -and β-receptors, there are several
types of each group of receptors (tab. 3, 4).
Table 3
Comparative characteristics of the autonomic and somatic nervous system.
Properties
Somatic nervous
system
1.Higher centers 4-5 layer of cells of
the precentral gyrus
of the frontal lobe
of the cerebral
Vegetative nervous system
Parasympathetic
Sympathetic part
Some areas of the cerebral cortex
Anterior nuclei
the hypothalamus
21
Posterior nuclei
the hypothalamus
2. Executive
centers
cortex
motor neurons of
the anterior horns
of the spinal cord
3. The presence
of peripheral
ganglia along
the efferent part
of the reflex arc
No
4. Characteristic
of efferent
neural fibers
long uninterrupted,
type A (speed 70120 m/s)
5.Transmitters
and receptors
6.Innervated
organs
7. Effect on the
organs
8. Activation
conditions
Acetylcholine
N-cholinergic
receptors
Skeletal muscles
Rising activity
Control activity of
skeletal muscles
Cranial part: nuclei
of cranial nerves: III, autonomic nuclei of
VII, IX, X
the lateral horns of
Sacral part:
the spinal cord CVIII
autonomic nuclei of
to LII
the lateral horns of
the spinal cord SII-SIV
Intramural ganglia
Paravertebral
(in the walls of the
ganglia
innervated organs)
(sympathetic trunk)
and extramural
and prevertebral
ganglia near the
ganglia- (superior
innervated organ
and inferior
(submandibular,
mesenteric plexus
sublingual, parotid..)
and celiac trunk)
Preganglionic type B Preganglionic type
(3-18 m/s), long
B (3-18 m/s), short
postganglionic type postganglionic type
C (0,5-3 m/s) –
C (0,5-3 m/s) –
unmyelinated, short unmyelinated, long
Preganglionic fibers:
Preganglionic
Acetylcholine
fibers:
N-cholinergic
Acetylcholine
receptors
N-cholinergic recep.
Postganglionic
Postganglionic:
fibers:
Noradrenalin
Acetylcholine
α, β- adrenergicM-cholinergic
receptors
receptors
All organs, except:
All organs
sweat glands, adrenal
gland, CNS, uterus,
most of the vessels
Inhibitory effect
activation
dominates at rest,
controls normal
22
dominates during
times of stress,
only
physiological
processes
physical activity
Influence of autonomic nervous system on the organs (fig. 14).
Figure 14.Autonomic nervous system – innervation of the inner organs.
Table 4
Localization ofα, β -adrenoreceptors and results of their activation
Type of
receptor
Localization
Smooth muscles
vessels
Myocardium
Result of activation
blood Narrowing
Increase in force of contraction *
23
α1
α2
Type
receptor
Spleen
Circular muscle of iris
Liver
CNS
Adrenergic axon`s endings
Blood vessels
Adrenergic neurons
CNS
Adipose tissue
Islet tissue of pancreas
of Localization
Sinus node
β1
Increase of excitability, increase of
frequency of heart contractions
Increase the force of contractions
Increase conductivity
Increase automatism
Myocardium
Atrioventrycular node
Bundle of His
Liver, skeletal muscles
Arterioles,
especially
arterioles
of
skeletal
muscles
Smooth muscles ofbronchi
Pregnant uterus
β2
β1and β2
Contraction
Distension of pupil
glycogenolysis increases
Increase in impellent activity
Decrease secretion of catecholamines
Narrowing
Decrease activity
Calming; analgesia, oppression of the
structures
activating
cardiovascular system
Oppression of lipolysis
Decrease of secretion of insulin
Result of activation
Increase glycogenolysis
Relaxation
Relaxation
Weakening
and
stoppage
of
contractions
Islet tissue of pancreas
Increase of secretion of insulin
Sympathetic nerves` ending Increase
of
secretion
of
neurotransmitter
Cholinergic nerves` ending Increase of secretion of acetylcholine
Adipose tissue
Increase of lipolysis
Juxtoglomerular tissue of Increase of secretion of renin
kidneys
24
Research the functional status of vegetative nervous system of the person.
Research of functional status vegetative nervous systemhas huge diagnostic valueina
clinical practice. Status of reflexes and also results of some special functional tests
characterize tone of vegetative system. Methods of clinical research of vegetative
nervous system may be conditionally divided into following groups:
1. questioning the patient: presence of burning pains;sleep disturbance,
urinationabnormalities, disturbances of functions of intestines; recurring decrease and
increase of arterial pressure; bradycardia or tachycardia, pain of death, etc.;
2. research of dermographism (white, red, elevated, reflex);
3. research of painful vegetative points;
4. cardiovascular tests: capillaroscopy, research of reaction of skin on the influence of
ultra-violet irradiation, adrenalinic and histamine skin tests, hygrophilous test,
oscillography, plethysmography, measuring skin temperature, some reflexes
(oculocardiac, clinostatic, orthostatic, etc.);
5. electrophysiological tests - research of electroskin resistance ;
6. measuringamount of biologically active substances - catecholamine (adrenaline,
noradrenalin) and others in urine and blood, definition of choline esterase activity in
blood.
Research of functional status vegetative nervous system also includes
examination of sweating, sensitivity of zones by Zaharyne-Ged.
Exercise1.Investigation of vegetative tone of the person by index Kerdo.
Index Kerdo allows estimating a status of vegetative tone by the parameters describing
a status of cardiovascular system (arterial pressure (AP) and heart rate).
Equipment: monometer with phonendoscope, a stop watch.
Procedure. Measure arterial pressure at the person in sitting position after 5 mines of
rest. Examine the AP (mm hg) and a pulse rate (heart rate).
Registration of the results.
1. Using these parameters calculate vegetative index Kerdo (VIK, %) by the formula:
VIK = (1 - AP/heart rate) •100 (%)
2. Make estimation of your own initial vegetative tone:
normotonia: VIKfrom-10 to+10 %,
sympaticotonia: VIK more + 10 %,
vagotonia: VIK less-10 %.
Observations, results and conclusion.
Exercise2.Investigation of vegetative tone by methodof questionnaire design.
Equipment: the table-questionnaire.
25
Procedure. Following questions of tab 15. At each positive answer put a sign "+", that
will correspond to one point. After filling the table-questionnaire count up sumunder
corresponding columns and formulate one of three conclusionsby prevalence of a sum
in one of three columns:
eitoniaor normotonia (relative vegetative balance);
vagotonia (prevalence parasympathetic influences);
sympaticotonia ( prevalence of sympathetic influences).
Make the conclusion about your initial vegetative tone and compare it to the conclusion
from the previous problems.
Observations, results and conclusion.
Table 5
A questionnaire for reference estimation of an initial vegetative tone in human*
Symptoms and
clinical indexes
Skin:
Color
Dermographism
Body temperature
Body weight
Appetite
Cardiovascular
functions:
Frequency of heart
beats
Arterial pressure
The sensation
heartbeats in rest
Pains in the
heartregions
Respiratory
parameters:
Frequency of breath
The volume of
breath
Physical efficiency,
activity
Dream
Sympaticotonia
Normotonia
Vagotonia
Pale
Normal
Pink, white
Propensity to raise
Red
Normal
Propensity to grow thin
Normal
Increase
Propensity to
tachycardia
Normal
Normocardia
Propensity to
reddening
Red, towering
Propensity to
decrease
Propensity to
obesity
Decrease
Propensity to
bradycardia
Propensity to raise
Propensity to
hypotension
Is not
characteristic
Are often
Is raised
Accordingly
toage
Is not
characteristic
Is not
characteristic
Normal
Is raised
Normal
Is decreased
Is raised
Normal
Is decreased
Restless
Quiet
Deep
Is characteristic
Are possible
26
Is decreased
Psychoemotialfeatures
Absent-mindedness,
often hyperexcitability
Steadiness
Apathy
Amount of points
* The table is presented in a reduced variant.
Exercise 3. Investigation of vegetative reactance of the person by extracardial
reflexes.
Some cardiac reflexes have important diagnostic, and sometimes medical, value.
Reflex by Danini-Ashner, sinocardial (Goering-Chermaac), solar (Tome-Ru) are most
well known reflexes. All of them arise during irritation corresponding reflexogenic
zones and conduct to stimulation of vagus nerves influences on heart. Centripetal ways
of these reflexes reach nuclei of these nerves in medulla oblongata; centrifugal ways to
heart begin from them.
Equipment: a stop watch. Researchis carried out on the human being.
Procedure. Consistently carry out research of three reflexes.
1. Oculocardiac (Daniini-Ashner) reflex. Tested personsits on a chair, having
relaxed, during 5-6 minutes. Count up the initial pulse at the tested person. Then ask
him to close his eyes. Put four fingers of hands to temporal surface of person's head and
press on his eyes with the thumbs slowly during 10-20 sec. Do not use very strongly
press on both closed eyes, then quickly stop pressing. Again count up frequency of
pulse. Pulse is counted up right after with pressings on eyeballs and through 5 minutes
after the termination of influence.
The maximal delay of pulse is registered on 15-30-thto second and lasts 20-60
second after the termination of pressure.At healthy people the number of intimate
reductions is slowed down on 4-10 beats /minute (normal type).If thedelay of pulsewill
be more than on 10 beats /minute reaction is considered strengthened (vagothonic type).
Ifpulse becomes frequent,it is the perverted reaction; atabsence of shifts -reaction is
negative (sympaticothonic type).
2. Cervical vegetative (carotid sinus) reflex; test by Chermac. Make this test
through 8-10 minutes after previous exercise. Wait for initial pulse value will be
recovered. Define a pulsation in the field of forward border of theuppertierce of
sternocleidomastoid muscle (a zone of projection of carotid bifurcating). Carry out easy
constant pressing on it during 20-30 seconds. With other hand count up frequency of
pulse for 30 seconds. Writedown results in the table. Delay of pulse on 6-12 beats
/minute is characteristic for normal parasympatheticreactions (vagotonia); delay over
12 beats /minute testifies to increase of tone of vagus nerve.
27
Table 6
Test
Oculo-cardiac
reflex
Carotid sinus
reflex
Results of research of vegetative reflexes
Initial value of pulse, Size of change of pulse in test
per min
Normal
test
Norm al
test
60-65
from -2,0 to -10,0
60-65
from -4,0 to -10,0
60-65
-4,0 --10,0
Observations, results and conclusion.
Exercise 4. The analysis of vegetative reactance of the person by cold test method
Cold test allows investigation of vegetative reactance.
Equipment: a tonometer with a phonendoscope, a stop watch, a glass with very cold
water. Research is carried out on the human being.
Procedure. Define arterial pressure (the AP, mm hg) and a pulse rate (heart rate, /mines)
at the tested person in sitting position. Then ask him to dip his right hand into the glass
with cold water for1 minute. In 0, 5 and 1 minutes from the beginning of test, and also
every minute after the hand is taken from a glass with cold water, the AP (mm hg) and
heart beats are investigated repeatedly.
1. Write your results into the table 7.
Table 7
Parameter
SP, (systolic
pressure)mm Hg
DP, (diastolic
pressure)mm Hg
Hear rate,
per min
VIK, %
Initial
values
Vegetative reactivity
(minute of inspection)
1-st
2-nd
3-rd
4-th
0,5
28
5-th
2. Estimate size of vegetative reactance by change the AP (mm Hg) and heart rate, using
formula Kerdo.
VIK = (1 - AP/heart rate) •100 (%)
(VIK – vegetative index Kerdo).
Observations, results and conclusion.
Exercise5. Other vegetative tests
Simple tests may be made in any conditions. In spite of a seeming simplicity of these
methods, they give the important information about status of vegetative regulation at
the person.
Equipment: a stop watch, a couch, a wooden stick with the sharp end.
Procedure. Two students participate in exercise - one is investigated, another performs
tests. Carry out following manipulations consistently.
A. Clinostaticreflex (test by Daniepolopol)
Investigated slowly passes from vertical position in horizontal. In response pulse
is slowed down on 4 - 6 beats per minute (positive reaction) or on 8-12 beats per
minute(sharply positive reaction) that depends on reflex increase of a tone of vagus
center.
B. Orthostatic reflex (test by Prevel)
Investigated, being in horizontalposition, slowlystands up. In response pulse will
be increase on 6-24 beats /min (positive reaction); more than on 24 beats /min - sharply
positive. It depends on reflex increase of a tone of sympathetic system.
C. Dermographism-a parameter of a tone of precapillars of skin.
White dermographismis causedby fast drawing of an easy stroke on a skin (with
the sharp end of a wooden stick). In 8 -20 sec after irritation there will be a white strip
which is kept from 1 up to 5-10 minutes(in norm).
Red dermographismis caused by a slow drawing strong stroke on a skin with the
blunt end of a stick. Through 5-15 sec there will be red strip which is kept from 1,5
minutes up to 1- 2 hours(in norm).
Toweringdermographism.Make stroke on a skin by strong pressure with the
holeof stick. Through 1-2 minutes there will bepalecylinder, which in norm is kept for
a long time. Unlike two previouskinds of dermographisms, it occurs in healthy people,
toweringdermographism is characteristic only for sickpeople.
Reflex dermographism.Make stroke on a skin with strong pressurewith sharp end
of the stick. Through 5-30 sec there will appear pink -red (rare white) spots. There sizes
may be about 1-6 sm. Contours are rough. These changes are kept in norm from 30 sec
up to 10 minutes.
29
Hair (pilomotor) reflex (test byToma). This reflex is caused by mechanical
irritation: tingle skin, friction, a touch of an ice, ether and chloroaethyle irritation. In
response there will be a goose-pimples in the area of irritation.
Observations, results and conclusion.
THEME 2. PHYSIOLOGY OF RESPIRATION
Lesson 1. Physiology of breathing. External breathing. Control of Respiration.
The questions for studying:
1. Functions of respiration.
2. Pleural cavity and intrapleural pressure. Surface tension of the intraalveolar fluid.
3. Mechanics of breathing.
4. Pulmonary volumes and capacities. Respiratory dead space.
5. Composition of gases in air. Gases exchange in the lungs.
6. Oxygen and carbon dioxide transport by blood.
7. Dissociation curve of haemoglobin. Factors influencing the shape of the curve.
Gases exchange in the tissues.
8. Oral and nasal breathing, their peculiarity and connection.
9. Nervous control of respiration. Respiratory control center. Its localization and
composition.
10. Mechanism of rhythmic respiration.
11. Central chemoreceptors, peripheral chemoreceptors. Their significance in
regulation of breathing.
12. Pulmonary mechanoreceptors. Their significance in regulation of breathing.
13. The importance of the hypothalamus and cerebral cortex in the regulation of
respiration.
1. Functions of respiration.
Respiration is a chemical reaction that happens in all living cells, including
plant cells and animal cells. It is the way that energy is released from glucose so that all
the other chemical processes needed for life can happen. The major functions of the
respiratory system are: supplying our bodies with oxygen from cellular respiration as
well as disposing of the carbon dioxide waste product that comes from cellular
respiration.The respiratory system and the circulatory system are very intimately
coupled with each other in this process.Other functions of the respiratory system also
include our sense of smell or olfaction as well as speech (fig. 15).
30
The term respiration includes three functions:
1) ventilation(breathing);
2) gas exchange, which occurs between the air and blood in the lungs and
between the blood and other tissues of the body;
3) oxygen utilizationby the tissues in the energy-liberating reactions of cell
respiration.
Figure 15. Major functions of the respiratory system
The respiratory system is divided into a conducting zone, which conducts the air
to the alveolus and a respiratory zone, which is the site of gas exchange between air and
blood (fig. 16). The exchange of gases occurs across the walls of respiratory alveoli.The
conducting zone structures: pharynx, larynx, trachea, right and left mainstem bronchi
and bronchioles. The respiratory zone consists of respiratory bronchioles and alveoli.
Figure 16. Organs of respiratory system
31
Breathing is a process as a result of which the organism receives oxygen and
emits carbon dioxide. We distinguish five stages of breath.
1. Exchange of gases between environment and alveoli of lungs.
2. Exchange of gases between alveoli and blood. Gas exchange in lungs.
3. Blood transport of gases.
4. Gas exchange in tissue.
5. Actual tissue respiration.
Ventilation and the exchange of gases (oxygen and carbon dioxide) between the
air and blood are collectively called external respiration.
Gas exchange between the blood and other tissues and oxygen utilization by the
tissues are collectively known as internal respiration.
2. Pleural cavity and intrapleural pressure. Surface tension of the intraalveolar
fluid.
The pleural cavity is formed by visceral and parietal pleura. Negative (below
atmospheric) pressure in this cavity is caused by elastic draft of a lung and a superficial
tension of surfactant. Elastic draft is caused by elasticity of pulmonary fabric and
directed to a lung root (fig. 17). Surfactant is a proteinaceous and lipidic complex. If
pressure in a pleural cavity becomes equal to atmospheric (for example, at an injury)
there is pneumothorax. At the same time lungs are tightened to a root and cease to
participate in breath.
Figure17. Pulmonary pressure
3. Mechanism of breath and exhalation.
At a breath of and ribs rise outside and upward. The dome of a diaphragm is flattened.
Lungs follow the thorax increasing in volume. It occurs because between an external
surface of lungs and an internal surface of a thorax there is a pleural cavity. Pressure in
32
this cavity is lower than a mercury column at 6-9 mm. The exhalation occurs passively.
At the same time the dome of a diaphragm rises and ribs fall. The volume of a thorax
decreases (fig.18).
Figure18. Mechanism of breath and exhalation
4. Pulmonary volumes and capacities. Respiratory dead space
The maximal volume of all the airways in an adult is typically 5 to 6 liters. This volume
includes those of the nasopharynx, the trachea, and all airways down to the alveolar sacs
(tab. 8).
Table 8
Lung’s volumes
Volume and capacities:
Typical ranges
IRV= Inspiratory reserve volume
1,0-2,5L
TV= Tidal volume
ERV= Expiratory reserve volume
0,3-0,9 L
1,0-1,5 L
RV = Residual volume
0,5 L
TLC = Total lung capacity
3,5-7,0 L
IC= Inspiratory Capacity
(TV+IRV)
2,5-3,5 L
FRC = Functional residual capacity
(RV+ERV)
2,3-2,7 L
VC= Vital capacity
4,0-7,0 L (male);
3,0-5,0L (female)
6,0-8,0 L/min
Minute ventilation
Rate of breathing (RB)
12-18 breaths per minute
33
1. Tidal Volume (TV) – is the volume of air breathed in and out during quiet
respiration (about 500 ml).
2. Inspiratory Reserve Volume (IRV) – the volume of air that can be breathed in
by maximum inspiratory effort after an ordinary inspiration.
3. Expiratory Reserve Volume (ERV) – the volume of air that can be breathed out
by maximum expiratory effort after an ordinary expiration.
4. Residual Volume (RV) – is the amount of air which remains in the lungs after
maximal expiration. It can only be expelled out from the lungs by opening the
chest and allowing the lungs to collapse.
5. Inspiratory Capacity (IC) – maximum volume of air that can be inspired from
the end-expiratory position, i.e. TV+IRV.
6. Vital Capacity (VC) – it is the volume of air that can be breathed out by maximal
expiratory effort after a maximum inspiration. It equals TV+IRV+ERV.
Respiratory dead space
The air which remains confined in the upper respiratory tract with each inspiration
and is not available for gaseous interchange constitutes what is known as “dead space
air”. It amounts roughly to 150 ml.
Functions of anatomical dead space:
1. Inspired air is saturated by water vapour before it reaches the alveoli of the lungs.
2. To remove the particulate matter in sizes more than 2,0 mm from the inspired air
before it is delivered to the alveoli.
5. Composition of gases in air. Gases exchange in the lungs.
The alveolar air differs in composition from that of the inspired (atmospheric) air.
The reasons for this difference are:
1. Only a part of the alveolar air is replaced by inspired air as explained previously.
2. There is continuous absorption of O2 from the alveolar air by pulmonary venous blood
– the alveolar air, therefore, is poorer in oxygen.
CO2 is added continuously to the alveolar air by the pulmonary venous blood –
the alveolar air, therefore, is richer in CO2.The inspired air is dry but gets saturated with
water vapour during its passage through the respiratory tract.Since some of the space in
the alveoli is now occupied by water vapour – the space available for other gases is
diminished (tab. 9).
Expired air. It has been noted that part of the expired air (“dead space” air) is
atmospheric air rich in O2 and poor in CO2. As expiration progresses the expired air
becomes a mixture of “dead space” air and that the last part of the expired air is pure
34
alveolar air. The expired air, therefore, is richer in O2 but poorer in CO2 as compared
to alveolar air.
Table 9
Composition of the inhaled, exhaled and alveolar air
Gases
Inspired air (%)
Alveolar air (%)
Expired air (%)
𝐎𝟐
20,93
14,0
16,0
С𝐎𝟐
0,03
5,5
4,5
Diffusion.Diffusion means movements of a substance from an area of high
concentration to an area of low concentration.In the present context the diffusion of O 2
from alveoli to pulmonary capillaries and of CO2in the reverse direction is to be
considered N2 being metabolically inert may be left out of discussion.
The following points are to be noted in this connection:
1) Gases in the alveoli are dissolved in small quantity of alveolar fluid and are in
equilibrium with partial pressure of the respective gases in alveolar air.
2) Gases in the blood of pulmonary capillaries are also dissolved in water of the plasma
where these exert a tension.
6. Oxygen and carbon dioxide transport by blood
The average values of tension of O2 and CO2 in these two areas are given below
(tab. 10):
Table 10
Average values of tension of O2and CO2
O2, mm Hg
P CO2, mm Hg
Alveoli
100
40
Venous blood
40
46
Diffusion, therefore, takes place in the direction shown by the arrows through the
alveolo-capillary membrane which consists of:alveolar epithelium – thin epithelial cells
together with its basement membrane; thin interstitial space between above and below;
capillary endothelium together with its membrane.Alveolo-capillary membrane is freely
permeable to respiratory gases and thus ensure rapid diffusion of O2 and CO2 through
them in the direction shown by the arrows from the point of high pressure to the point
of low pressure (fig. 19).
35
Figure 19. Blood transport of carbondioxide.
Oxygen comes to tissue. Carbon dioxide comes out of tissue. One part of it is just
dissolved in blood. It is the first form of transport of carbon dioxide. The other part of
carbon dioxide comes to an erythrocyte and contacts hemoglobin. Carbohemoglobin is
formed. It is the second form of transport. In erythrocytes carbon dioxide contacts water
forming an coal acid. Reaction is catalyzed by enzyme of a carbanhydrase. Coal acid
dissociates on ions H+ + HCO3-. HCO3-leaves an erythrocyte and forms bicarbonates of
sodium and potassium in plasma. It is the third form of transport. In plasma there is also
a reaction CO2+H2O↔H2CO3. The coal acid which is formed at the same time is the
fourth form of transport.
36
7. Dissociation curve of haemoglobin. Factors influencing the shape of the curve
Blood in the systemic arteries, at a PO2, of 100 mmHg, has a percent
oxyhemoglobin saturation of 97% (which means that 97% of the hemoglobin is in the
form of oxyhemoglobin). This blood is delivered to the systemic capillaries, where
oxygen diffuses into the cells and is consumed in aerobic respiration.Blood leaving in
the systemic veins is thus reduced in oxygen; it has a PO2 of about 40 mmHg and a
percent oxyhemoglobin saturation of about 75% . A graphic illustration of the percent
oxyhemoglobin saturation at different values of PO2 is called an oxyhemoglobin
dissociation curve.Theoxyhemoglobin dissociation curve is S-shaped, or sigmoidal. The
fact that it is relatively flat at high PO2 values indicates that changes in PO2 within this
range have little effect on the loading reaction. One would have to ascend as high as
10,000 feet, for example, before the oxyhemoglobin saturation of arterial blood would
decrease from 97% to 93%. At more common elevations, the percent oxyhemoglobin
saturation would not be significantly different from the 97% value at sea level (fig.20).
Figure 20. The oxyhemoglobin dissociation curve
Blood transport of oxygen. Oxyhemoglobin dissociation curve (fig.21).Oxygen is
transferred by blood in two forms: in physical dissolution and in the form of
oxyhemoglobin
[Hb(O2)4]
S= ----------------------------------[Hb] + [Hb (O2)4]
Oxyhemoglobin dissociation curve shows that the main condition of development and
dissociation of oxyhemoglobin is the partial tension of oxygen in blood.
37
Figure 21. Oxyhemoglobin dissociation curve
8. Nervous control of respiration. Respiratory control center
Inspiration and expiration are produced by the contraction and relaxation of
skeletal muscles in response to activity in somatic motor neurons in the spinal cord. The
activity of these motor neurons is controlled, in turn, by descending tracts from neurons
in the respiratory control centers in the medulla oblongata and from neurons in the
cerebral cortex (fig. 22).
Figure 22. Regulation of breathing
The I neurons project to and stimulate spinal motoneurons that innervate the
respiratory muscles. Expiration is a passive process that occurs when the I neurons are
inhibited, presumably by the activity of the E neurons.
38
The inspiratory neurons are located primarily in the dorsal respiratory group, and the
expiratory neurons in the ventral respiratory group.
The dorsal group of neurons regulates the activity of the phrenic nerves to the
diaphragm, and the ventral group controls the motor neurons to the internal intercostal
muscles.The activity of the I and E neurons varies in a reciprocal way to produce a
rhythmic pattern of breathing.
The activity of the medullary rhythmicity center is influenced by centers in the
pons. As a result of research in which the brain stem is destroyed at different levels,
two respiratory control centers have been identified in the pons.
One area—the apneustic center —appears to promote inspiration by stimulating the I
neurons in the medulla. The other area—the pneumotaxic center —seems to antagonize
the apneustic center and inhibit inspiration (fig. 23).
Figure 23. Pons. The rhythmicity center in the medulla oblongata directly controls breathing, but it
receives input from the control centers in the pons and from chemo-receptors.
9. Central chemoreceptors, peripheral chemoreceptors
The automatic control of breathing is also influenced by input from receptors
sensitive to the chemical composition of the blood. There are two groups of
chemoreceptors that respond to changes in blood PCO2, pH, and PO2. These are the
central chemoreceptors in the medulla oblongata and the peripheral chemoreceptors.
The peripheral chemoreceptors include the aortic bodies, located around the aortic arch,
and the carotid bodies, located in each common carotid artery at the point where it
branches into the internal and external carotid arteries (fig. 24).
Chemoreceptors in the medulla most sensitive to changes in the arterial PCO2 and
H+ arе located in the ventral area of the medulla oblongata. The chemoreceptors in the
medulla are ultimately responsible for 70% to 80% of the increased ventilation that
occurs in response to a sustained rise in arterial PCO2.
39
Figure 24. The peripheral chemoreceptors (aortic and carotid bodies) regulate the brain stem
respiratory centers by means of sensory nerve stimulation.
10. Mechanism of rhythmic respiration.
The automatic control of breathing is regulated by nerve fibers that descend in the
lateral and ventral white matter of the spinal cord from the medulla oblongata. The
voluntary control of breathing is a function of the cerebral cortex and involves nerve
fibers that descend in the corticospinal tracts. The separation of the voluntary and
involuntary pathways is dramatically illustrated in the condition called Ondine's curse
(the term is taken from a German fairy tale). In this condition, neurological damage
abolishes the automatic but not the voluntary control of breathing. People with Ondine's
curse must remind themselves to breathe and they cannot go to sleep without the aid of
a mechanical respirator (fig. 25).
40
Figure 25. The automatic and voluntary control of breathing.
11. Pulmonary mechanoreceptors.
Effects of pulmonary receptors on ventilation. The lungs contain various types of
receptors that influence the brain stem respiratory control centers via sensory fibers in
the vagus nerves. Irritant receptors in the wall of the larynx, and receptors in the lungs
identified as rapidly adapting receptors, can cause a person to cough in response to
components of smoke and smog, and to inhaled particulates
The Hering-Breuer reflex is stimulated by pulmonary stretch receptors. The
activation of these receptors during inspiration inhibits the respiratory control centers,
making further inspiration increasingly difficult. The Hering-Breuer reflex appears to
be important in maintaining normal ventilation in the newborn.
Exercise 1. Spirometry.
Principle. The functional condition of lungs depends on age, sex, size, physical
development and other factors. The most widespread characteristic of a condition of
lungs is measurement of pulmonary volumes. They testify to development of organs of
breath and functional reserves of respiratory system.
Spirometry is a method of determination of vital capacity of lungs and volumes of air
making it. It is possible to measure volume of inspired and expired air by means of a
spirometer.
Equipment. Spirometer (fig. 26), spirit cotton wool.
41
Figure 26. Spirometer
Procedure:
1. Measurements make standing.
2. Take a spirometer; establish a scale of the spirometer on zero position.
3. Clean a mouthpiece of spirometer with the spirit cotton wool.
4. First make the maximal breath, after that make as much as possible deep expiration
into the spirometer. On a scale of spirometer it is defined vital capacity lungs.
5. For measurement of respiratory volume make a quiet breath through a nose and then
easy expire air into spirometer. On a scaleof spirometer it is defined tidal volume (size
of respiratory volume).
6.Compare size of vital capacity of lungs to due or proper vital capacity which calculate
with nomogram (fig. 27).
The exact amount of vital capacity depends on age, sex and size of the individual.
Observed VC may show a variation of 10% from the predicted VC in normal subjects.
Pulmonary ventilation = Tidal volume x Respiratory rate.
42
Calculate parameters of Vital Capacity of lungs (percentage) by the formula:
X = 100 - (Vital capacity [measure] / Vital capacity [proper]) x 100%.
Norm of parameter is 12-15%.
Men
age
VC
height
Women
age
VC
height
Figure 27. Nomogram
Normal ventilation in an adult (75 kg) is about 6 L per minute with a respiratory rate of
12 breaths per minute and Tidal volume of 0,5 L.
Observations, results and conclusion.
Exercise 2. Spirography.
Principle. If the spirometer is equipped with a recording device (spirograph), it can be
also used for graphic measurement of the total ventilation per unit time (fig. 28).
Purpose. To record the changes in lung volume during quiet and maximal effort
respirations.
Equipment. Spirograph, spirit cotton wool.
Procedure.
1. The spirographmust be turned on. The mouth-piece and the nose-clip must be
sterilized.
2. Sit in a relaxed position.
3. Take the mouth-piece in your mouth and put on the nose-clip.
4. Breathe quietly into the mouth-piece. The Spirograph records tidal lungvolume.
5. Make the maximal inspiratory and expiratory effort into the mouth-piece, the
Spirograph records inspiratory and expiratory reserve volumes.
43
6. At the end of the spirographic recording make a maximal inspiratory effort and
then exhale all air very fast. The volume of air exhaled in one second under these
conditions is called the forced-expiratory volume in one second (FEV). In healthy
young adults, FEV is about 80% of VC.
7. Calculate the value of lung volumes and capacities. Pay attention that one point
on vertical channel of the recording paper equals 200 ml of air and one point on
horizontal line is corresponding to 12 sec (5 points equals 1 min).
Figure 28. Spirogram.
Observations, results and conclusion.
Exercise 3.Pneumography.
Principle. Pneumography is registration of the respiratory movements. It allows to
determine the frequency and depth of respiration, as well as to determine the ratio of
duration of inhalation and exhalation. In adults the frequency of respiratory movements
is amount 12-18 per minute, children have more rapid breathing. The frequency and
depth of respiration are changed during muscular work. Change the frequency and depth
of respiration is observed during swallowing, conversation, after delay the breathing etc.
Pneumography may be determine with different methods. Pneumosensor with Mare’s
capsule is the most simple and available method for registration of the respiratory
movements. Strain gage transducer, rheostatatic and induction sensors may be used for
44
pneumography, but these methods need in use electronic intensive and registering
apparatus (fig. 29).
Equipment. Kymograph, cuff from sphygmomanometer, Mare’s capsule, tripod, Tjoint, rubber tubing, time controller, liquid ammonia.
Figure 29. Pneumography. A - graphic registration of respiration by means of Mare’s capsule. 1. wide
cuff, 2.rubber tube, 3. Mare’s capsule, 4.kymograph, 5. time marker, 6. T-joint, 7. universal tripod.
Pneumograms:а- quiet breathing, b- at inhalation ammonia, c- during speech, d- after hyperventilation,
e- after voluntarydelay the breathing, f- during physical exercises.
Procedure.
1. Assemble the apparatus for registration respiratory movements as itdemonstrated in
figure 28. Cuff from sphygmomanometer must be fixed on the chest of person. Then
join the cuff from sphygmomanometer with capsuleby means of T-joint and rubber
tubing. Bring in registering apparatus a small quantity of air through the T-joint. Engage
kymograph and time controller.
2. Record the respiration:
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а) at rest condition (quiet breathing);
b) at maximum inhalation and at maximum exhalation (lung vital capacity);
c) during the conversation;
d) at swallowing;
e) at inhalationammonia (cotton wool which is wetted with ammonia is carried to the
nose of person;
f) after voluntarydelay of respiration;
h) after hyperventilationof lungs;
i) during muscles exercise.
3. Draw the curve of pneumograms into your copy-book. Determine the phase when
swallowing and speech are realized. Compare nature of respiration changes under
influence from different factors.
Observations, results and conclusion.
46
THEME 3. DIGESTIVE SYSTEM
Lesson 1. Digestion in Oral Cavity and Stomach.
Questions for studying.
1. Function of digestive system: motility, secretion, digestion, absorption, storage,
elimination.
2. Mouth. Secretion of saliva.
3. Mastication. Deglutition. Swallowing center.
4. Esophagus. Peristalsis in esophagus. Lower esophageal sphincter.
5. Stomach. Gastric glands. Gastric juice.
6. Digestion and absorption in stomach.
7. Regulation of gastric secretion by nervous and hormonal mechanisms.
1. Function of digestive system
The main functions of the digestive system include:
1. Ingestion of food.
2. Digestion of food.
3. Secretion of various digestive juices.
4.Absorption of water, salts, vitamins and end productions of food digestion.
5. Excretion – heavy metals, toxins, certain alkaloids etc.
6. Movement.
7. Erythropoiesis – in stomach – intrinsic faсtor, extrinsic factor – vitamin B12.
Maturation of the erythroid cells (pernicious anaemia).
8. Regulates blood reaction.
9. Regulates blood sugar.
10. Maintains water balance.
Motility. Food moves through the digestive tract due to a process called peristalsis,
which is the movement of muscles in the GI tract that move the food through the
digestive system. This involves the breakdown and mixing of ingested nutrients all the
way through the elimination of undigested waste from the body.
Secretion. This is the release of enzymes, hormones, and other substances that help the
body digest the food that is eaten. Hormones tell the body when to produce digestive
juices and signal the brain when you are hungry or full.
Digestion. Ingested nutrients including proteins, fats, carbohydrates, vitamins,
minerals, and water are reduced into molecules small enough to pass through the lining
of the gut and so they can enter the bloodstream. The digestive system breaks down
foods we consume so the body can use them for energy, growth, and cell repair. Proteins
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break down to amino acids. Fats break down to fatty acids and glycerol. Carbohydrates
break down to simple sugars.
Absorption. The digested nutrients pass from the gut into the blood so the circulatory
system or lymph system can pass them on to the rest of the body to use or store. The
lymph system absorbs fatty acids and vitamins. The blood carries simple sugars, amino
acids, glycerol, and some vitamins and salts to the liver. The liver stores, processes, and
delivers these nutrients to the body when needed.
There are five digestive juices:saliva;gastric juice;pancreatic juice;intestinal
juice;bile.One juice does not contain all the enzymes necessary for digesting all the
different types of blood stuff.Saliva contains only carbohydrate – splitting enzymes;
gastric juice contains both fat-and protein-splitting enzymes.One digestive juice cannot
digest a particular type of food up to completion.Gastric juice digests protein up to the
stage of peptone;pancreatic juice carries the digestion of peptone further up to lower
peptide;the latter is digested completely up to amino acids by succusentericus.Reactions
of the digestive juice are not all same (acid and alkaline).
2. Mastication.
Mastication (chewing), in which food is crushed and mixed with saliva to form a bolus
for swallowing, is a complex mechanism involving opening and closing of the jaw,
secretion of saliva, and mixing of food with the tongue. Mastication is programmed in
the lower brainstem.
Masticatory movements comprise exceedingly complex and coordinated
neuromuscular events. The masticatory activities require the coordinated activity of
several groups of muscles attached primarily to the mandible. During mastication, there
is an opening phase, a closing phase, and an occlusal phase.
Figure 30. Teeth anatomy
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3. Deglutition. Swallowing center. Regulation of deglutition
Deglutition is the process of swallowing any food stuff into the body, particularly
passing from the mouth, to the pharynx, and down through the esophagus. The food
stuff ingested and swallowed is called a bolus.There are three stages of deglutition. The
first stage is the voluntary closure of lips and tooth approximation. The second stage is
the involuntary peristalsis so that the bolus would be propelled down the esophagus. At
this stage, the nasal passage and pharyngeal airway are shut. The third stage is the
passing of the bolus along the length of the esophagus and then into the stomach, again,
through involuntary peristalsis.
Chewing and initial phase of swallowing are carried out by skeletal musculature (fig.
31). The center of swallowing is located in a medulla. The innervation is provided with
the trigeminal, glossopharyngeal and vagus nervous. The food lump is forced back by
the tongue that starts a swallowing reflex through mechanoreceptors. The lump gets into
a throat, the nasal cavity and airways are reflexively closed. Stretching of the top part
of a gullet starts a peristaltic reflex which promotes the food down. Both ends of a gullet
have sphincters: upper and lower. The lower sphincter protects mucous of a gullet from
gastric juice.
Figure31. Phases of swallowing
5. Mouth. Secretion of saliva.
In a mouth the nutrition is split, moistened and there is an initial stage of splittng of
carbohydrates with the participation of a saliva amylase (fig. 32).Saliva is formed in
three larger paired salivary glands: parotid gland, submandibular gland, sublingual
gland and in glands mucous checks, a palate and a pharynx.
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Figure 32. Digestion in the oral cavity
Salvia is formed in two stages. At first lobes of special cells make the isotonic
primary saliva similar to the structure of blood plasma. At the second stage during
passing across the removing canals of gland its ionic structure changes. pH saliva
changes from subacidic to alkalescent.
6. Composition and functions of saliva. Total amount of saliva is 1200-1500 ml in 24
hours. Consistency of saliva is slightly cloudy (presence cells and mucin). Reaction of
saliva is usually slightly alkaline (pH – 6,02-7,05).
Composition of saliva:Water – 99,5%, Solids – 0,5%. 1) cellular constituents
(epithelial cells); 2) inorganic salts(0,2%), NaCl, KCl, Ca2+ phosphate; 3)organic
(0,3%): a) enzymes – amylases (ptyalin); lipase, lysozyme;b) mucin;c) urea, amino
acids,ets.; 4) gases (O2, CO2); 5) kallikrein (vasodilatation).
Functions of saliva.
I. Mechanical functions.
1. It keeps the mouth moist and helps speech.
2. It helps in the process of mastication of the food stuff and in preparing it into a
bolus, suitable for deglutition.
3. It dilutes hot and irritant substances and thus prevents injury to the mucous
membrane.
4. Constant flow of saliva washes down the food debris and there by does not allow
the bacteria to grow.
II. Digestive functions.Amylase (ptyalin) and maltase (in traces) converts maltose into
glucose.
III. Excreted functions.Saliva excretes urea, heavy metals and antibiotics, ets.
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IV. Helps in the sensation of taste.Saliva acts as a solvent and it thus essential for
taste.
V. Helps water balance.Saliva keeps the mouth moist.
VI. Buffering action.Mainly bicarbonate and to a lesser extent phosphate and mucin
present in saliva act as buffers.
VII. Bacteriolytic action. Lysozyme – it dissolves the cell wall of many bacteria and
finally kills them.
7. Regulation of saliva secretion by sympathetic and parasympathetic nervous
Salivation is controlled by salivary center in medulla through autonomic nervous
system. The salivation reflex under the influence of smell and taste of food is stimulated.
Big salivary glands have a sympathetic and parasympathetic innervation. Salivary
secretion is the only digestive secretion that controlled only neural factors (fig. 33).
Figure 33. Salivation is regulated by central nervous system
At increase of a tone of sympathetic nerves it is allocated with a little viscous and
rich organic substance of saliva. At increase of a tone of parasympathetic nervous a lot
of liquid saliva is emitted (fig. 34).
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Figure 34. Parasympathetic nervous regulation of salivary secretion
Parotid gland is located below the ear and over the masseter. Submandibular is under
lower edge of mandible. Sublingual is deep to the tongue in floor of mouth. All salivary
glands have ducts that empty into the oral cavity (exocrine glands). Serous glands –cell
secrete a watery fluid – e.g. parotid. Mixed glands secrete both mucus and a serous fluid
– e.g. submandibular and sublingual. Chemical digestion begins with enzyme salivary
amylase and lingual lipase.
8. Stomach. Gastric glands. Gastric juice
The stomach is a hollow organ that is part of the gastrointestinal system, and it is
responsible for functions including the formation of chyme, synthesis of proteins
necessary for vitamin absorption, microbial defenses, and propagates the peristaltic
reflex. Contrary to popular thought, the stomach does not contribute to the absorption
of any nutrients. This organ can is in the peritoneal cavity, located in the left upper
abdominal quadrant or in the epigastric abdominal region that acts to relay ingested food
between the nervous system and the endocrine system. Gastric acid secretion, peristaltic
propulsion, and other physiologic functions of the stomach are finely controlled by the
integration of the enteric nervous system, parasympathetic nervous system, and the
secretion of various neurohormonal molecules (i.e., gastrin, HCl acid, intrinsic factor,
bicarbonate, mucus, etc.)
As a component of the alimentary canal (i.e., the tubal passageway for ingested
food to be digested, absorbed, then excreted as waste), the stomach’s physiological
function is structured around creating an environment where the food ingested can be
safely acted on by proteolytic enzymes and acidic solutions. There are pathologic
consequences that can develop with the failure of the gastric mucosa to isolate the
lumenal contents from the surrounding peritoneal cavity.
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The gastric juice is produced by stomach glands, located in its mucosa. The main
cells secrete pepsinogens. These are proteases, proteolytic. Acid cells secret the
hydrochloric acid and Kastl’s factor. Roles of the hydrochloric acid: activation of
pepsinogen, that turns into pepsin; possesses bactericidal action; promotes opening of a
pyloric sphincter; Kastl’s factor is a B12 vitamin carrier. Mucoid cells produce slime
(mucin).The mucosa is composed of surface epithelial cells and glands. The basic
structure of the stomach wall is similar to that of other regions of the gastrointestinal
(GI) tract, therefore, the wall of the stomach consists of both mucosal and muscle layers.
The stomach can be divided, based on its gross anatomy, into three major segments (fig.
35): 1) A specialized portion of the stomach called the cardia is located just distal to the
gastroesophageal junction and is devoid of the acid-secreting parietal cells. 2) The body
or corpus is the largest portion of the stomach; its most proximal region is called the
fundus. 3) The distal portion of the stomach is called the antrum. The surface area of the
gastric mucosa is substantially increased by the presence of gastric glands, which consist
of a pit, a neck, and a base. These glands contain several cell types, including mucous,
parietal, chief, and endocrine cells; endocrine cells also are present in both corpus and
antrum. The surface epithelial cells, which have their own distinct structure and
function, secrete image and mucus.
Figure 35. Anatomy of the stomach
Gastric juice is a thin watery acid digestive fluid secreted by glands in the mucous
membrane of the stomach (fig. 36).
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Figure 36. Composition of gastric juice
2. Regulation of gastric secretion by nervous and hormonal mechanisms
A small amount of a gastric juice is developed at rest. It is basal secretion. At meal there
is a stimulated secretion.
There are three phases of gastric secretion (fig. 37):
I.
Complex-reflex (cerebral) phase. In this phase the gastric juice is allocated at a
sight and flavor of food and at getting food into a mouth. It is appetite juice.
II.
Gastric phase of gastric secretion begins with the moment of getting of a food
lump into a stomach. It includes nervous and humoral components.
Nervous component: the food lump irritates the stomach mechanoreceptors. An impulse
from them comes to a medulla to cores of a vagus and to intramural nervous plexuses.
From there impulses go to a stomach. The terminations of these nerves allocate
acetylcholine which strengthens secretion of the hydrochloric acid and pepsinogen.
Humoral component: at getting of a food limp into a stomach a hormone gastrin
is emitted. It contacts the receptors on the acid cells and strengthens the secretion of
hydrochloric acid. Hormone gastron, on the contrary, slows down the secretion of
hydrochloric acid.
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Figure 37. Regulation of gastric secretion by nervous and hormonal mechanisms
III. Intestinal phase of gastric secretion. It begins with the moment of a chymus
getting into intestinal. This phase also includes nervous and humoral components. Thus,
there is mainly inhibition of gastric secretion.
Nervous component: the chymus irritates mechanoreceptor of intestine and an impulse
comes to a medulla to cores of a vagus and intramural ganglion. From them impulses
come to a stomach to fundic glands.
Humoral component: getting of a chymus into a duodenum gut stimulates
allocation of secretin and enterogastrone which slow down secretion of hydrochloric
acid.
Exercise 1. Influence of Saliva on Starch.
Principle. Saliva contains chiefly salivary amylase orptyalin and traces of maltase.
Salivary amylase (α-type) whose origin in the saliva, acts on starch (which is mostly
amylopectin type) and contains straight chains held by l,4'-a-glucosidic linkages and
branch chains whose branch points are l,6'-a-glucosidic linkages. Maltase acts on
maltose.
Salivary amylase (ptyalin) acts on boiled starch only. It cannot penetrate the
intact cellulose covering of the unboiled starch particle. Optimum reaction is slightly
acid (pH 6,5), but it can also act in neutral or slightly alkaline medium. Strong acid (such
55
as HC1 of gastric juice) destroys ptyalin. Optimum temperature is about 45°C. At 60°C
it is destroyed. Ptyalin digests starch up to the maltose stage only.
Equipment. Glass test tubes, marker, crude and boiled starch, saliva, dropping pipette,
water, water bath, thermometer, a spirit-lamp, matchbox, solution of iodine, ice cubes.
Procedure. Experience spends under the following scheme. Collect saliva in test tubes,
preliminary to rinse a mouth pure water.
Take 5 test tubes.
1 test tube – 2ml of saliva + 1 ml of boiled starch (paste).
2 test tube - 2 ml of saliva + crude starch.
3 test tube - 2 ml of boiled saliva (boil it above a spirit-lamp) + 1 ml of boiled starch.
4 test tube - 2 ml of saliva + 1 ml of boiled starch.
5 test tube - 2 ml of dog’s saliva + 1 ml of boiled starch.
Place 1, 2, 3, 5 test tubes into the water bath with temperature +38-40°C, 4 test tube in
a glass with ice for 30 minutes.
After 30 minutes take out all test tubes and add a solution of iodine (do reaction
of iodine and starch). The color of solution becomes dark blue if there is some starch in
the solution (tab. 10).
Table 10
Influence the saliva on the starch.
№№
tube
1
2
3
4
5
Content of a test tube
Reaction with iodine
2ml of saliva + 1 ml of boiled starch
2 ml of saliva + crude starch
2 ml of boiled saliva + 1 ml of boiled starch
2 ml of saliva + 1 ml of boiled starch
(put in a glass with ice)
2 ml of dog’s saliva + 1 ml of boiled starch
Observations, results and conclusion.
Exercise 2. Determination of Mucin in Saliva.
Equipment. Glass test tube, saliva, dropping pipette, water, 10 % solution of an acetic
acid (CH3COOH).
Procedure:
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1.
Pour 1 ml of 10 % solution of an acetic acid (CH3COOH) into the test tube with
saliva.
2. Observe acid mucin in the form of white deposit settles on a test tube bottom.
Observations, results and conclusion.
Exercise 3. Influence of Gastric Juice on Milk.
Principle. The main protein of milk is casein, a complex phosphoprotein. The enzyme
rennin causes clotting of milk. It liberates paracasein from casein which is precipitated
as calcium paracaseinate. Although rennin is absent in human stomach, but chymosin
is present in infant stomach which does the same action of rennin of ruminants.
Chymosin is distinct from pepsin. Other proteases presented in the stomach can convert
casein to paracasein. Trypsin and chymotrypsin digestions convert it to
phosphopeptones containing phosphoserine.
Digestion of milk. Three constituents of milk require digestion: 1) Protein –
Caseinogen. Lactalbuminand Lactglobulin are digested in the same way as proteins successively by pepsin, trypsin and erepsin. 2) Fats. They undergo the same process of
digestion as other fats. 3) Lactose is digested by lactase to glucose and galactose.
Equipment. Glass test tubes, marker, dropping pipette, water, water bath, thermometer,
a spirit-lamp, matchbox, solution of gastric juice, milk, СаСО3.
Procedure.
Take 3 test tubes.
1 test tube - 2 ml of gastric juice + 2 ml of milk.
2 test tube - 2 ml of boiled gastric juice (boil it above a spirit-lamp) + 2 ml of milk.
3 test tube - 2 ml of gastric juice neutralized by СаСО3 + 2 ml of milk.
Place all test tubes into the water bath at temperature + 40оС for 15 minutes.
After 15 min. take out test tubes and observe the effect of clotting milk under influence
of gastric juice (tab. 11).
Table 11
Influence of gastric juice on milk.
№№
tube
1
2
3
Content of a test tube
2 ml of gastric juice + 2 ml of mi
2 ml of boiled gastric juice + 2 ml of milk
2 ml of gastric juice neutralized by CaCO3 + 2
ml of milk
57
Result
Observations, results and conclusion.
Lesson 2. Digestive System. Digestion in Intestine. Role of Bile in Digestion.
Questions for studying.
1. Stomach. Gastric glands. Gastric juice.
2. Digestion and absorption in the stomach.
3. Regulation of gastric secretion by nervous and hormonal mechanisms.
4. Pancreas. Pancreatic secretion. Regulation of pancreatic secretion.
5. Liver. Functions of the liver. Secretion of bile by the liver.
6. Small intestine. The regions of the small intestine. Secretion of the small
intestine (mucus and intestinal digestive juices). Regulation of small intestinal
secretion.
7. Intestinal contractions and motility. Peristalsis, segmentation. Slow waves.
Function of small intestine.
8. Large intestine. Function of large intestine. The act of defecation. Digestion of
carbohydrates, fats and proteins in gastrointestinal tract.
9. Anatomical basis and basic mechanisms of absorption. Fluid and electrolyte
absorption in the intestine.
10. Regulation of the gastrointestinal tract. Autonomic nervous system, enteric
nervous system, paracrine regulation, hormonal regulation.
Pancreas. Pancreatic secretion. Regulation of pancreatic secretion
Pancreatic juice has alkaline reaction due to bicarbonates (pH = 8-8,3). Enzymes
are a part of pancreatic juice – proteolytic (trypsinogen, chemotrypsinogen, elastase,
procarboxypeptidase A and B). They are developed by gland in an inactive form and
activated only in a duodenum gleam by enzyme of enterokinase.
- Lipase, splits fats;
- Amylase (amylolytic enzyme), splits amylum and glycogen.
There are two ways of pancreatic secretion regulation: Nervous (vagus strengthens
secretion, sympathetic nerves block it) and humoral (hormones secretin and
pancreozymin), (fig. 38).
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Figure 38. Pancreatic juice and bile are secreted into the duodenum
On the figure 39 is given a scheme of regulation of pancreatic juice secretion.
Figure 39. Regulation of pancreatic juice secretion
Liver. Secretion of bile by the liver
Liver produces and releases bile (fig. 40). Components of bile secretin hepatocytes and
epithelial cells come into bilious channels. Out of digestion process bile gathers in a gall
59
bladder. In the course of digestion bile sphincter is removed through Odi’sin a
duodenum. One liter of bile is allocated per a day. The bile includes bilious acids. They
emulsify fats, participate in absorption the long-chain of fatty acids.Also cholesterine,
bilirubin, bicarbonates are a part of the bile. pH of bile is equal to seven point eight.
Bilious acids from intestines are soaked up in blood, through a portal vein come back to
a liver and there they secrete into bile again. It is a hepatoenteric circulation.Bile
secretion is regulated: 1) Secretion by hypatocytes (parenchymal) depends on
concentration of bilious acids in blood of a portal vein. 2) Ductal secretion is stimulated
by hormone secretin.
Also cholesterine, bilirubin, bicarbonates are a part of the bile, bile’s pH = 7,8. Bilious
acids from intestines are soaked up in blood, through a portal vein come back to a liver
and there they secrete into bile again. It is a hepatoenteric circulation.
Bile secretion is regulated by: 1) hepatocytessecretion(parenchymal). It depends on
concentration of bilious acids in blood of a portal vein; 2) Ductal secretion is stimulated
by hormone secretin.
Figure 40. The role of liver in digestion
Small intestine
There are two types of digestionin a small intestine: abdominal digestion and
parietal digestion. Abdominal digestion happens in a gut cavity with the participation of
enzymes of pancreatic juice, intestinal juice and bile. At the same time polymers of food
are split to oligomer (fig. 41). Parietal digestion happens with the participation of
enzymes of intestinal juice on a brush border of a small intestine. At the same time
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oligomers are split to monomers and monomers are absorbed up.Components of
intestinal juice are produced by Brunnerov and Lieberkuhn glands, enterocytes,
epitheliocytes and beaker cells. In a small intestine there is a final digestion and
absorption of food. Enterokinase, peptidase (the leucine amino-peptidase, nuclease and
others split peptides to amino acid), amylase, lactase, sucrose, maltose, lipase are a part
of intestinal juice. Cations and anions are also a part of intestinal juice. Intestinal juice
pH is from 7.8 to 8.0.Regulation of intestinal secretion is carried out by local reflexes
(with participation of a gastroenteric nervous system), a nervous system with
participation of a CNS (stimulationof n. Vagus and sympathetic nerves block) and with
participation of hormones (secretin, gastric inhibitory peptide).
Figure 41. Two types of digestion in a small intestine: abdominal digestion and parietal
digestion
Intestinal contractions and motility
The peristalsis of small intestine can be divided into propulsive (pushing) and
nonpropulsive segmental movement (fig. 42). Nonpropulsive peristalsis movement
promotes the best mixing of chymus and digestive juice. We distinguish nonpropulsive
segmental activity, tonic contraction, pendular movements and fluctuation of fibers. At
the end of digestion process one or two powerful waves of contraction of longitudinal
muscles move the remain of contents of small intestine to large intestine. It is propulsive
peristalsis. Motility of small intestinal is locally regulated with participation of
gastroenteric nervous system, sympathetic nerves (block) also parasympathetic nervous
(vagus stimulates) and with participation of hormones (gastrin, secretin,
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glucagon).Motility of colon carries out two function: moving the fecal masses forward
and storage the fecal masses. Normal antiperistalsis happens here (from an anus).
Figure 42. Motility of a small and thick intestine
Anatomical basis and basic mechanisms of absorption
The product of food digestion is not absorbed in a mouth cavity because it is not
split completely (fig. 43). In stomach water, mineral salts, a small amount of amino
acids, weak solutions of alcohol are absorbed. The main absorption of products of
splitting happens in a small intestine. After full digestion of the carbohydrates arriving
with food there are formed monosaccharide: glucose, fructose and galactose. Fructose
is absorbed passively into the blood. Glucose is absorbed in two stages: secondary active
transport (symport with sodium ions) in enterocyte also from enterocyte in blood on the
mechanism lite diffusion. The galactose is also transferred by secondary active
transport. Proteins are split into amino acids, di- and tripeptide. Amino acids are
absorbed by secondary active transport (symport with sodium ions) by means of special
protein-carriers. Di- and tripeptide are also absorbed by secondary active transport
(symport with hydrogen ions) by means of nonspecific carrier (transports various
peptides) – protein. Fats are split into monoglycerides and fatty acids. Short- and
medium – chain – length fatty acids are absorbed passively in blood. Long chain fatty
acids with bilious acids form micelles in gut gleam. Micelles come into contact with a
membrane of enterocyte. Bilious acids remain in a gut gleam.In enterocyte triglycerides
are formed from fatty acids which with apoprotein form chylomicrons. Get to the lymph
by an exocytosis. Fat – soluble vitamins A, D, E and K are similarly absorbed.
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Water-soluble vitamins are absorbed by active transport with participation of
special carriers.
Figure 43. Absorption in various departments of a digestive tract
Regulation of the gastrointestinal tract
Gastrointestinal tract, gastroenteric nervous system includes bodies of neurons
which lie in a wall digestive tubes and form full reflex arches. These reflex arches can
work without CNS’ influence(fig.44). There are two big plexuses can be distinguished:
intermuscular (Auerbac’s plexus, plexusmyentericus). It is located between layers of
longitudinal and ring muscles and proceeds along all gastrointestinal tract. The second
one is submucous nervous plexus (Meyssner`s` plexux, plexux submucosus). It lies in a
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submucous layer. Both plexuses innervate a smooth, blood vessels and cells of an
epithelium of a digestive tube.
Value of own nervous system of a gastrointestinal tract is visible on the example
of illness of Girshprung – congential defect of both plexuses. Babies with this pathology
arenot capable of empting an intestine independently. The gastrointestinal tract
innervation is also carried out by means of a vegetative nervous system (a
parasympathetic a sympathetic innervation – efferent nerves) and a visceral afferent
innervation. Parasympathetic preganglionic fibers come in structure of Nerves Vagus
from a medulla and as a part of pelvic nerves from sacrum department of a spinal cord.
The parasympathetic system sends fibers to exciting and inhibitory cells of an
intermuscular nervous plexus. Preganglionic sympathetic fibers begin from cells in side
horns of sternal-lumbar department of a spinal cord. Their axons innervate blood vessels
and approach cells of nervous plexuses, inhibiting their exciting neurons.Visceral
afferent begin in a wall of a gastrointestinal tract and as a part of the n.vagus,
n.splanchnice and n.pelvici go to a medulla, sympathetic ganglia and a spinal cord.
Figure 44. The innervation of the gastrointestinal tract.
Exercise 1. Role of Bile in Digestion.
Principle. The most abundant substance secreted in the bile is bile salts, but there are
also bilirubin, cholesterol, lecithin and the usual electrolytes of plasma, secreted or
excreted in large concentrations. In concentrating process in gallbladder, water and large
portions of electrolytes are reabsorbed by gallbladder mucosa, but essentially all other
constituents, including especially bile salts and lipid substances cholesterol and lecithin,
are not reabsorbed and therefore become highly concentrated in gallbladder bile.
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It is very important that bile contains no digestive enzyme because of the presence of
bile salts which 1) have a detergent action on the fat particles in food and in other words
help to emulsify fat globules so that they can be digested by the intestinal lipases, 2)
increases the activity of intestinal lipase and other proteolytic enzymes, and 3) help in
the absorption of fatty acids, monoglycerides, cholesterol, and other lipids from
intestinal tract. Bile is secreted continually by the liver and then the bile is stored in the
gallbladder until it is needed in the gut. The gallbladder then empties the bile into the
intestine in response to cholecystokinin.
Purpose. To investigate the emulsifying or detergent function of bile and to observe the
influence of bile by the filtration of oil.
Equipment. Glass test tubes, glass funnels, glass slides, dropping pipettes, paper
filters, bile, vegetative oil, water.
Procedure.
1. Moisten thoroughly one of the paper filter with bile, another – with water.
2. Put both paper filters into glasses funnels.
3. Pour 2 ml vegetable oil on the paper filters and after 45 min study the filtration of
oil through the paper filters.
Observations, results and conclusion.
Exercise 2. Identification Test on Bile Pigments and Bile Salts.
Principle. Bile consists of salts of bilious acids and bile acids: taurocholic and
glycocholic acids.
Equipment. Glass test tubes, dropping pipettes, bile, 10% solution of sugar,H2SO4,
water.
Procedure.
1. Pour 0,5 ml of bile into the test tube and add 5-6 drops 10% solution of sugar.
2. Add to the test solution very carefully 2 ml H2SO4.
3.Put the test tube into the glass with cold water.
4. Observe the color of mixture becomes red in some minutes. It is positive reaction of
presence of taurocholic and glycocholic acids in the bile.
Observations, results and conclusion.
Exercise 3. Gmelin’s Test on Bile Pigments.
Principle. The bile pigments are porphyrin compounds and constitute about 15-20%
of the total solids of the liver bile. They can be detected by Gmelin’s test.
65
Equipment. Glass test tubes, dropping pipettes, bile, HNO3 (Nitric acid), water.
Procedure.
1. Pour 1 ml HNO3 in one test-tube and pour 2 ml bile to another test tube.
2. Add very carefully bile to Nitric acid avoiding mixing of liquids.
3. Observe formation of multi-colored rings on border of two liquids. The mixture has
positive reaction, which shows different degree of oxidation of bilirubin.
Observations, results and conclusion.
66
THEME 4. METABOLISM AND NUTRITION
Questions for studying.
1. Metabolism and interchange of energy in human being. Plastic and energy role of
nutrients.
2. Laws of thermodynamics in living organisms.
3. Energy storage (anabolism) and energy liberation (catabolism).
4. Energy balance. Positive energy balance, negative energy balance.
5. Methods of determine energy expenditure.
6. Direct calorimetry.
7. Indirect calorimetry. Complete and incomplete gas analysis.
8. Respiratory quotient (RQ) and its significance for calculation energy expenditure.
Respiratory quotient during physical activity.
9. Basal metabolism, conditions for its determination, significance. Factors which
influence on level of basal metabolism.
10. Positive energy balance, negative energy balance. Basal metabolic rate.
11. Labor exchange energy consumption during different kinds of labor.
12. Irreplaceable componentry of food.
13. Plastic and energy value of nutrients.
14. Role of trace elements and vitamins in nutrition.
15. Ballast substances – kinds, physiological significance.
16. Replaceable componentry of food.
17. Food intake. Regulation of food intake.
18. Energy equivalents of the carbohydrate, protein and lipid. Nutritional equipment.
Nitrogenous balance.
19. Physiological fundamentals of clinical nutrition.
The specific function of cell metabolism is energy transformation subordinated to laws
of thermodynamics. Fermentative breaking up organic substances (catabolism) is
accompanied with discharge of energy. And fermentative synthesis (anabolism) is
accompanied with consumption of energy. Metabolism of carbohydrate and lipids is
primary process formative energy.
The definition metabolism with meaning literally “change” is used to refer to all the
chemical and energy transformations that occur in the body. The body’s metabolism
encompasses all of the chemical processes involved in energy production, energy
release, and growth. These processes can be anabolic (formation of substances) or
catabolic (breakdown of substances).
67
The animal organism oxidizes carbohydrates, proteins, and fats, producing principally
CO2, H2O and the energy necessary for life processes. CO2, H2O, and energy are also
produced when food is burned outside the body. However, in the body, oxidation is not
a one-step, semiexplosive reaction but a complex, slow, stepwise process called
catabolism, which liberates energy in small, usable amounts. Energy can be stored in
the body in the form of special energy – in rich phosphate compounds and in the form
of proteins, fats, and complex carbohydrates synthesized from simpler molecules.
Formation of these substances by processes that take up rather than liberate energy is
called anabolism. Both anabolism and catabolism are reversible chemical reactions but
growth and loss of tissue mass (breakdown of tissue) depends on predominance of one
over the opposite reaction. Metabolism may be broadly defined as the sum of all
chemical and physical processes involved in producing and expending energy from
exogenous and endogenous sources, in synthesizing and degrading structural and
functional tissue components, and in disposing of resultant waste products. These
processes are of fundamental importance to all cells, tissues, organs, and systems.
Cells of internal organs consume about 25% of all chemical energy for their needs. It
can be spent, for example, for active transport, protein synthesis, contraction of smooth
and skeletal muscles. Subsequently, this energy is converted into heat.
The intensity of energy exchange is usually estimated in units of thermal energy. In the
international SI system of units, the joule (J) or kcal is adopted as the basic unit of
energy, 1kcal = 4.19 kJ.
From 100% of the food energy of a modern person, its consumption can be
represented as follows:
1. 50-60% - spent on life support
2. 10-15% - for the assimilation of the food itself (specific-dynamic effect of food)
3. 30-40% - to ensure human activity, including: work in production, at home,
outdoor activities, physical education.
The energy balance of the body is calculated as the difference between the incoming
and outgoing energy. Energy exchange in an adult is considered balanced if the income
is equal to the consumption. If the income is higher than the consumption, the energy
balance is called positive. If the expense exceeds the income - negative.
The body's energy consumption depends on:
I. Individual typological factors:
1. Surfaces of the body and masses.
2. Age (the child is 4 times higher).
68
3. Gender (women are 5% lower than men, except for pregnancy).
4. Genetic features (severity of non-phosphorylating oxidation - insensitivity to cold,
hyperthyroidism).
5. Body temperature (an increase in body temperature by 1 ° C, accelerating chemical
reactions, increases energy exchange by 5%).
II. Environmental conditions:
1. Climate (high temperature in the tropics does not require large energy consumption;
in a cold climate, energy exchange increases by 5-7 times).
2. Biorhythms: daily - during the day energy exchange is higher than at night; seasonal
- summer and winter.
3. Psycho-emotional environment: the modern standard of beauty (fashion) and food
consumption; food traditions.
Energy consumption is determined by the value of the main exchange. Basal metabolic
rate (BMR) is the amount of energy expended to maintain the vital activity of the body
and the constancy of body temperature under conditions of physiological rest. The basal
metabolism in an adult is about 1 kcal per 1 kg of body weight per hour (1 kcal / kg /
hour) and is equal to - 1,700 kcal / day for men, and 1,500 kcal / day for women, which
is 10-15% less than in men.
Factors affecting basal metabolism are from gender, age, weight and body length. The
same person from 20 to 40 years old can have fluctuations in basal metabolism from ±
7 to ± 10% (normal).
The purpose of determining the basal metabolic rate is to clarify the type of exchange,
that is, to clarify the question of the presence of deviations from an energetically
balanced state.
Research is carried out under standard conditions:
- at a comfortable temperature (18-20°С);
- in a calm state, because emotional stress increase metabolism;
- lie down, but do not sleep, because sleep reduces energy metabolism by about 10%;
- on an empty stomach, at least 12 hours after the last meal.
Energy consumption per day (total metabolism) consists of the following values:
1. Basic exchange - BMR
2. The specific dynamic action of food (DAF) is the cost of energy for motility,
secretion and absorption processes in the gastrointestinal tract.
3. Working increase - energy consumption during labor activity.
During physical exertion, the metabolic rate increases depending on the degree of
physical exertion. The more intense the work, the greater the value of the work
69
exchange. The acceleration of metabolism also occurs during mental stress, although
this is not only related to the needs of the brain. Predominantly, the increase in
metabolism during the period of mental work is a reflex increase in muscle tone.
Accounting for energy output
1. Determination of the BMR
2. Definition of general exchange.
Accounting for the arrival of energy
1. Accounting for the amount of nutrients,
consumed per day.
2. Calculation of the caloric value of
nutrients substances, i.e. the total amount
of energy, obtained with various nutritional
substances.
According to the obtained values of energy income and consumption, the energy
balance is estimated.
Methods for determining energy consumption (output).
I. Direct calorimetry.
II. Indirect calorimetry:
1. Method of complete gas analysis.
2. Method of incomplete gas analysis.
3. Calculation of the proper basal metabolism according to tables and formulas.
Exercise 1. Methods for determination of energy output.
Principle. Energy output can be determined by measuring the heat production of an
individual over a measured amount of time.
I. Direct calorimetry. A biocalorimeter is a completely sealed and heat-insulated
chamber, into which oxygen is supplied from special cylinders and excess carbon
dioxide and water vapor are removed. Inside the chamber are pipes filled with water.
During the movement of water through the pipes, it gradually heats up due to the heat
generated by the test subjects in the chamber (fig. 45).
Taking into account the amount of water flowing through the pipes and accumulating
in a special tank, as well as measuring its temperature with a special thermometer, the
amount of heat that was released over a certain period of time (per hour, day) is
calculated. Food and waste products are fed and removed through a special window.
The pump allows air to be removed and driven through the soda lime to remove excess
CO2, and also through sulfuric acid to absorb excess water. This method is the most
accurate, since it directly takes into account the amount of heat released by the body.
70
Figure 45. Biocalorimeter Benedict
II. Indirect calorimetry.
The process of heat generation can be judged indirectly, based on the amount of
oxygen consumed and carbon dioxide released, since the formation of heat in the body
is based on redox processes involving these gases.
1.Method of complete gas analysis.
The subject inspires atmospheric air. The expired air is collected in special air-tight bag
known as Douglas bag (fig. 46).
Figure 46. Douglas bag
The total volume of expired air collected in the bag at the end of experiment is measured
and the samples are analyzed for CO2 and O2 in Haldane gas-analysis apparatus or in
Scholander's micro-gas analysis apparatus. The amount of oxygen consumed and
carbon dioxide given off is calculated from the difference of percentage of O2 and CO2
71
between the atmospheric and expiratory air. The RQ and the caloric value of O 2 can
then be determined. The Douglas bag method can conveniently be used to measure the
energy output during different types of activities.
Respiratory quotient (RQ)
It is the ratio of the volume of CO2 produced by the volume of O2 consumed during a
given time. In healthy adult it is 0, 85 for a mixed diet. This is done by measuring the
volume of O2 consumed and CO2 produced during a given time with the help of Douglas
bag and other similar instruments.
Factors affecting RQ.
1. Role of diet.
a) In case of carbohydrate diet the RQ is unity. Because in carbohydrate diet the
volume of CO2 produced is same as the volume of oxygen consumed. This is due
to the fact that, in the carbohydrate molecule, the amount of O2 present is just
sufficient to oxidize the H present in the same molecule. Hence, external oxygen
is necessary only to convert the C of the molecule into CO2 . So that the volume
of O2 consumed and the volume of CO2 produced will the same. This is
represented in the following equation: C6H12O6 +6CO2=6CO2+6H2O
RQ=6CO2 / 6O2=1,0
b) In case of fats the RQ will be lowest and is about 0,7; because fat is an oxygenpoor compound. The oxygen present in it cannot fully oxidize the H of the
molecule. So that, oxygen consumed from outside, is used for two purposes: first,
for oxidizing C and producing CO2 and secondly, for oxidizing H giving H2O.
Consequently, the volume of CO2 produced will be less than the volume of O2
utilized. Hence, RQ will fall and will be about 0, 7.
c) In case of proteins the RQ is about 0, 8.
In any condition where fats are burnt chiefly (starvation, advanced diabetes, etc.), the
RQ is about 0,7. Whereas with a predominant carbohydrate combustion the RQ is
approach 1,0.
2. Effect of interconversion in the body. When carbohydrates are converted into fats in
the body, RQ will rise. Because in the process an oxygen-rich substances converted
into an oxygen-poor compound. So that some amount of O2 liberated from carbohydrate,
will be utilized for purposes of oxidation. Consequently, less oxygen will be needed
from outside. Hence, the amount of CO2 produced will be more than the amount of O2
consumed. So that RQ will rise. When fat is converted into carbohydrate just the
opposite effects will be produces and RQ will fall.
72
It is therefore evident that RQ value will indicate the following:
1. the type of foodstuff burning in the body or
2. the nature of conversion of one foodstuff into another in the body.
3. Acidosis. During acidosis CO2 output is greater than O2 consumption so RQ rises.
4. Alkalosis. Here the RQ will fall, because respiration is depressed and CO2 will be
retained in the body (i.e., less CO2 is produced).
5. Rise of body temperature will cause increased breathing and thereby will wash out
more CO2. It may increase RQ as in acidosis.
6. Diabetes. Little carbohydrate is burning; energy is supplied mainly by oxidation of
fats. Hence, RQ will fall. In such cases, if insulin is injected, carbohydrates will start
burning and RQ will rise.
7. Muscular exercise.
Value of determining RQ.
1. RQ acts as a guide, as to the type of food burning or the nature of synthesis taking
place in the whole body as well as a particular organ.
2. RQ is very helpful in determining metabolic rate.
3. Non-protein RQ helps in finding-out the proportion of the three foodstuffs that are
being utilized in the body.
4. Determination of RQ helps in the diagnosis of various pathological conditions, such
as acidosis, etc.
Table 12
Amount of heat produced per liter of O2 consumed at different RQ.
RQ
0,71
0.75
0,80
0,85
0,90
0,95
1,0
Calories evolved per liter of O2 consumed
4,795
4,829
4,875
4,921
4,967
5,012
5,058
Example.
1. The probationer expired 30 liters of air during 5 minutes. This amount of air
contains about 17% of O2 and 3, 5 % of CO2. The atmospheric air consists of
73
about 215 of O2; the expired air consists of 17% of O2. Consequently, organism
takes up (21-17) 4 ml of O2 and excrete 3, 5 ml of CO2. Determine the RQ:
RQ = O2 consumed / CO2 produced
RQ = 3,5 /4.0 = 0,87.
2. Than determine the oxygen calorific equivalent using the table 1. It is 4, 88.
3. Determine the Respiratory Minute Volume (RMV): RMV = 30 litres / 5 min = 6
liters per minute.
4. Calculate oxygen using per minute:
4 ml of O2 are used from 100 ml of air
X ml of O2 are used from 6000 ml of air
So: X = (6000x4):100 = 240 ml = 0, 24 litters.
5. Calculate the consumption of energy per minute by equalization: oxygen using per
minute multiply by oxygen calorific equivalent:
0, 24 x 4, 88 = 1б17 kcal.
6. Calculate the consumption of energy per hour:
1,17 х 60 = 70,2 kcal.
7. Calculate the consumption of energy per 24 hours:
70,2 x 24 = 1684 kcal.
Due to complications involved in direct calorimetry, heat output is calculated indirectly
from O2 consumption and CO2 output.
2. Method of incomplete gas analysis. Various apparatus may be used for this purpose,
such as Benedict – Roth apparatus and other apparatus of similar type. Benedict – Roth
apparatus is very useful for clinical purposes as the heat production
can be calculated in this type of apparatus by the oxygen consumption only without
determination of CO2 elimination. The subject is allowed to breathe from O2 reservoir
through a mouthpiece, the nose being clipped. The CO2 eliminated in expiration is
absorbed by soda lime to keep the O2 reservoir pure. The fall in the level of O2 during
the experiment is recorded which gives the value of CO2 consumption at the specified
time. In this method, respiratory quotient (RQ) of the subject is not determined and
the average RQ is taken as 0, 82. 4,825 Cal of heat is liberated at this RQ when 1 liter
of O2 consumed. The energy output during the experiment is calculated by multiplying
liters of O2 consumed at that time with 4,825.
74
The following table shows the amount of heat produced per liter of O 2 consumed, at
different RQ.
Exercise 2. The Basal metabolism calculation by Garris – Benedict’s tables.
Equipment: auxanometer, floor scales, standard tables for determination the BMR
amounts.
Procedure.
1. Determine probationer’s body weight and growth. Starting from sex, body weight,
age and growth determine the BMR amounts by appropriate tables. Computational
exercise. Man is 25 years old, growth - 180 сm, body weight - 75 kg. Calculation table
consists of two parts: table A and table B. Find out the probationer's weight in table A
(75 kg) and against it find number (1098 kcal).
2. Find out probationer’s age across on table B (25 years), on vertical line - growth (180
cm) and find number (732 kcal) at the intersection of lines. Sum up the number from
table A (1098 kcal) and table B (732 kcal). The sum is 1830 kcal / day, average statistical
level of the probationer’s BMR.
3. Calculate your own BMR by tables.
Observations, results and conclusion.
Exercise 3. Determination of Energy Output Diversion by Reed’s nomogram and
hemodynamic index.
Principle. The intensity of the metabolic processes which are proceeding in the
organism is accompanied with some changes in the internal organs activity, in case,
from the heart-vascular system side. This relation was investigated by researcher Reed.
His formula and nomogram allow estimate the percentage of deviation of probationer’s
main exchange (energy output) from normal level. If you know the probationer’s pulse
frequency and AD value, you can find out a diversion percent of energy output from
normal level by Reed’s formula and Reed’s nomogram.
Procedure.
75
1. It is necessary follow some conditions: probationer is lying on a medical couch; he
has an empty stomach, he has not any physical and psychical stress, comfortable
temperature in the room.
2. Determine a probationer’s pulse, measure diastolic and systolic AD. Count a pulse
pressure (PP = AD systolic – AD diastolic).
3. Counting method of diversion percent (DP) with Reed’s formula:
DP = 0,75 x ( HBF + PP*0,74)-72;
The result shows a divergence percent of energy output (the main exchange) from
normal level.
4. Counting method of diversion percent (DP) with Reed’s Nomogram
Match amounts of pulse frequency on the left scale and pulse pressure on the right scale
on the Reed’s nomogram (fig. 47). The crossing point on the middle line shows the main
exchange divergence value from normal in percent. Divergence till 10% - is normal.
Figure 47. Reed’s Nomogram.
Observations, results and conclusion.
Make a conclusion about taken results of your diversion percent of energy output to the
normal level.
76
Nutritional requirements. Regulation of food intake.
The aim of the science of nutrition is the determination of the kinds and amounts of
foods that promote health and well-being. This includes not only the problems of
undernutrition but those of overnutrition, taste, and availability. However, certain
substances are essential constituents of
any human
diet.
Essential Dietary Components
An optimal diet includes, in addition to sufficient water, adequate calories, protein,
fat, minerals, and vitamins
Caloric Intake and Distribution.
The caloric value of the dietary intake must be approximately equal to the energy
expended if body weight is to be maintained. In addition to the 2000 kcal/d necessary
to meet basal needs, 500-2500 kcal/d (or more) are required to meet the
energy
demands of daily activities.
The distribution of the calories among carbohydrate, protein, and fat is
determined partly by physiologic factors and partly by taste and economic
consideration. A daily protein intake of 1 g/kg body weight to supply the eight
nutritionally essential amino acids and other amino acids is desirable. The source of
the protein is also important. Grade I proteins, the animal proteins of meat, fish, and
eggs, contain amino acids in approximately the proportions required for protein
synthesis and other uses. Some of the plant proteins are also grade I, but most are
grade II because they supply different proportions of amino acid and some lack one
or more of the essential amino acids. Protein needs can be met with a mixture of grade
II proteins, but the intake must be large because of the amino acid wastage.
Fat is the most compact form of food, it supplies 9,3 kcal/g. However, it is also
the most expensive food. Indeed, internationally there is a reasonably good positive
correlation between fat intake and standard of living. In the past, Western diets have
contained large amounts (100 g/d or more). The evidence indicating that a high
unsaturated/saturated fat ratio in the diet is of value in the prevention of atherosclerosis
and the current interest in preventing obesity may change this. In Central and South
American Indian communities where corn (carbohydrate) is the dietary staple, adults
live without ill effects for years on a very low fat intake. Therefore, provided that the
needs for essential fatty acids are met, a low fat intake does not seem to be harmful,
and a diet low in
saturated fats is desirable.
Carbohydrate is the cheapest source of calories and provides 50% or more of the
77
calories in most diets. In the average middle-class American diet, approximately 50%
of the calories come from carbohydrate, 15% from protein, and 35% from fat. When
calculating dietary needs, it is usual to meet the protein requirement first and then split
the remaining calories between fat and carbohydrate, depending upon taste, income,
and other factors. For example, a 65-kg man who is moderately active needs about
2800 kcal/d. He should eat at least 65 g of protein daily, supplying 267 (65 × 4.1) kcal.
Some of this should be grade I protein. A reasonable figure for fat intake is 50-60 g.
The rest of the caloric requirement can be met by supplying carbohydrate.
Exercise 4. Analysis of the energy value of the daily student’s diet
Principle. Caloric value of the daily diet must cover all energy wishes of the
person with a registration of the food adaptation.
Procedure.
1. Compose approximate diet for one day for your own.
2. Calculate the energy value of your daily diet using the tables 13,14.
Observations, results and conclusion.
Make a conclusion about accordance or discrepancy of normal data, common energy
wastes (also with calculation of the work groups, age and etc.).
Exercise 5. Composing of the proper food diet with calculation of rational
nourishment principals.
Principle. During the constitution of the diet, next indicators are calculated:
Proportion between proteins, lipids, carbohydrates is taken:
1:1,1:4,1 – For men and women , who are occupied with a intellectual work;
1:1,3:5 – heavy physical work.
Daily energy value of the diet, taken as 100%, must supply proteins by 13%, lipids – by
33%, carbohydrates – by 54%.
Animal’s origin proteins must constitute 55% of the common proteins number.
Vegetative oils as indispensable fat acids source must compose till 30% of the common
lipids number.
Carbohydrates: starch – 75-80%, easily adoptable carbohydrates – 15-20%, cellulose
and pectin – 5%.
Proportion of calcium, phosphorus and magnesium must be 1:1,5:0,5.
Nourishments norms – daily dozes of the nutritious substances, which are indicating
balanced keeping in the food diet of proteins, lipids, carbohydrates, and also vitamins,
78
mineral substances and water. These foods must provide a great self feeling, health and
working ability of a person in the normal conditions.
Nourishment norms depends on the gender, age, physical and mental working and
other factors.
Due to this data, adult man with a lesser muscular loading must gain daily with food:
proteins 100-120 g, lipids 100g, carbohydrates 400-500g. Energy waste in this state is
50-60 kcal due to 1 kg of the body weight daily.
Procedure.
1. Compose students’ diet, due to the next data: A student is listening lections during 6
hours, works by his own 4 hours, free of studying 6 hours sleeps 8 hours. He is 20 years
old, 165 cm height, 65 kg weight. Energy wastes during the lections 145%, during self
studying 160%, during free time – 220% of the main exchange value.
2. Identify the main exchange value by the Benedickt’s formula:
a) formula for men:
K=66,473+ (13,752xW) + (5,003 x S) – (6,755 x a).
b) formula for women:
К = 655,096 + (9,563 x W) + (1,850 x S) - (4,676 . а),
where К — common warmth production, kcal; W — body weight, kg; S — height, cm;
а — age.
3. Put the meanings of the height and weight to the formula due to the gender of the
probationer.
4. Identify energy wastes during the lections listening, during the self studying,
relaxation and sleeping
5. Gained results add between each other and get a daily energy wastes.
6. Count the amount of proteins, lipids and carbohydrates (g), which is necessary to add
into the daily student’s diet, to compensate his energy wastes.
7. With the help of chemical composition table compose the diet for three nourishments.
Table 13
Nutritious substances and their energy value (kcal)
79
Products
proteins
lipids
wheat flour
cereals:
• buckwheat
• semolina
• millet
rice
macaroni
marrowfat
bread
loaf of bread
water-melon
green peas
cabbage
• white cabbage
• cauliflower
• sauerkraut
potatoes
potato starch
bulb onion
carrots
cucumber
garden radishes
red beet
tomato
orange
grape
cranberries
apple
fungi:
• fresh
• dried fungi
honey
sugar
chocolate
cocoa
shortcake
5,6
1,3
carbohy
drates
36,0
13,4
11,2
11,8
7,5
11,0
32,8
5,9
9,0
0,3
5,0
2,5
0,8
2,4
1,0
0,9
2,3
0,8
1,3
-
66,5
73,3
68,4
74,4
74,2
52,0
47,3
51,4
4,8
13,3
351
354
352
346
358
329
326
260
21
75
1,4
1,5
0,3
1,4
2,5
1,1
0,8
0,9
1,0
0,5
0,7
0,4
0,5
0,3
-
4,3
2,8
2,3
14,7
84,7
8,1
6,0
2,8
3,1
8,1
3,6
6,3
14,9
4,7
10,0
23
18
17
66
351
43
29
15
16
37
19
33
66
33
44
4,2
36,0
0,4
6,3
23,6
12,8
0,4
4,0
37,2
20,2
9,0
2,3
23,5
81,3
99,9
53,2
40,2
69,5
30
281
335
410
590
449
421
80
kcal
160
sponge-cake
plum jam
• butter
• vegetable oil
• cow milk
curdled milk
sour cream
cottage cheese
Dutch cheese
mutton
beef
pork
boiled sausage
chicken-meat
small sausage
hen's egg
fluvial perch
pike perch
cod
herring
5,6
0,2
39,1
-
40,5
74,7
553
310
0,5
3,3
3,5
33
2,5
13,2
21,7
12,6
14,2
14,2
12,3
9,7
14,7
10,7
8,9
9,7
13,7
83,5
99,8
3,7
3,5
3,7
30,0
20,0
28,4
13,1
8,3
18,5
14,8
6,3
10,0
10,3
0,4
0,4
0,3
0,5
4,7
16,4
3,9
2,3
2,4
1,2
—
2,4
0,4
—
—
—
781
928
77
144
67
203
253
361
173
135
230
193
98
159
142
40
43
59
Table 14
Energy value of some food.
rations
Portion, g.
150
150
150
1 piece (115 g)
1 piece (125 g)
1 slice (9 g)
1 slice (30 g)
150
1/2 of fish, 60 g
1 glass (250 g)
1. steak
2. rich pork
3. pigeon-chest
4. beef small sausage
5. milk sausage
6. boiled sausage
81
Energy value
of
one
portion, kсal.
357
528
168
350
466
15
257
138
110
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7. lard
1/ glass (80 g)
1 slice (30 g)
1 piece (30 g)
1 table-spoon (30 g)
1 piece (60 g)
1 table-spoon. (12 g)
1 table-spoon (10 g)
1 table-spoon (15 g)
1 table-spoon (15 g)
1 portion (25 g)
1 portion (60 g)
1 slice
1 slice (40 g)
8. filleted perch
9. freshly-saltedherring
10. milk 3,5 %
11. kefir 1,5 %
12. Edam 45 %
13. processed cheese
14. rich cottage cheese
15. hen's egg
16. butter
17. vegetable oil
18. mayonnaise
19. buckwheat
20. corn flakes
21. cooked rice
22. rye-bread
23. pizza
Observations, results and conclusion.
THEME 5. HIGHEST NERVOUS ACTIVITY
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Lesson 1. Methods of Investigation of Cerebral Hemispheres. Cortex Functions.
Investigation of Active Bioelectrical Processes in Brain. Functional Asymmetry of
Hemispheres Performing Sensor and Motor Functions.
Questions for studying.
1. Structure of cerebral cortex and functions of its different layers.
2. Functions of cerebrum.
3. Cerebral lateralization.
4. Areas in brain which control motor, sensory and other activities.
5. Association areas of cerebrum.
6. Methods of studying the cortex functions.
7. Electrical activity of the cerebral cortex. Electroencephalography.
8. Clinical use of the electroencephalogram (EEG).
9. The different types of brain waves (alpha, beta, theta and delta waves).
10.Physiological basis of EEG. Mechanism of desynchronization and synchronization.
11.Cortical evoked potential.
12.Cerebral Dominance.
Electrical activity of the cerebral cortex.
The electrical activity of the brain and cerebral cortex is the summary activity of
different types of neurons and nerve fibres. A large number of neurons, synapses and
various properties of synapses, such as inhibition, summation, facilitation- etc., are
integrated together to give rise rhythmic electrical potential changes which can be
recorded by electroencephalograph. The electrical activity of the cerebral cortex is
divided into two types- spontaneous and evoked. The spontaneous electrical activity of
the brain is the electroencephalogram (EEG) which is described below.
Electroencephalography
Like other cells, nerve cells also show changes of electrical potential during activity.
With an instrument called electroencephalograph the waves can be detected, amplified
and recorded. Such record is called electroencephalogram. Hans Berger, who was a
German scientist, first introduced the term electroencephalogram (EEG). Berger in
1929 recorded changes in the electrical potential by placing electrodes on the scalp of
the human beings. These electrical potentials were later investigated by Adrian and
Matthews.
Electroencephalogram (EEG)
I. Spontaneous electrical activity.
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The spontaneous electrical activity from the brain is recorded by the
electroencephalographic machine with the help of scalp electrodes through the lead is
called electroencephalogram which has been most effectively studied in human
beings. Electroencephalographic records may be bipolar or unipolar and consists of
different types of rhythmic waves. Bipolar is the record of potential fluctuations
between two cortical electrodes, whereas the unipolar electrode is the record of
potential differences between a cortical electrode and an indifferent electrode placed
on some part of the body.
Alpha, beta, theta and delta waves. In normal human subjects four types of waves
are recorded, e.g., alpha, beta, theta and delta (fig 48).
Figure 48. Diagrammatic representation of normal electroencephalographic
α-alpha, β-beta, θ- theta and Δ-delta waves.
Alpha waves. Alpha waves (rhythm) are the most prominent synchronised rhythmic
potential changes, found with eyes closed or in dark, when the brain is under quiet rest.
Usually found in the occipital cortex, but also obtained in frontal and parietal regions.
This rhythm is marked in occipitoparietal region. Any mental exertion, even with closed
eyes, will disturb. The alpha waves disappear when eyes remain open. This alpha wave
is disappeared with a replacement of fast, irregular and low voltage activity without any
dominant frequency just after opening the eye. This phenomenon is known as α -block.
This α-block is due to synchronisation of regular (synchronised) α-rhythm by any kind
of sensory stimulation. This desynchronisation response is also called arousal or
alerting response (fig 49).
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Figure 49. Diagram shows the change of alpha rhythm after opening and closing eyes.
Visual stimuli, mental concentration, etc., abolish alpha waves. During deep sleep,
the alpha waves disappear entirely and with a specific mental activity the alpha waves
are replaced by asynchronous high frequency low-voltage waves. The dream is accompanied by alpha waves. The alpha waves cannot occur without the connection of the
reticular activating system. It is postulated that the reverberation between thalamus and
cerebral cortex and also the recruiting response of the thalamus are responsible for the
cause of the periodicity of the alpha waves. Rate—8-12 Hz or cycles per second,
amplitude—highest average 50 microvolt.
Beta waves. Usually found in the parietal and frontal regions of the scalp. Rate—
about 18 -60 Hz, amitude—5-10 microvolts (less than alpha waves)—low voltage fast
waves (fig 52).
Types: Beta I waves have a frequency about twice that of alpha waves and disappear
during reaction of mental activity, but such waves are replaced by asynchronous lowvoltage waves. Beta II waves appear during tension or during intense activation of the
central nervous system.
Figure 50. Normal electroencephalogram from different cortical areas in man showing alpha and
beta waves during awake with closed eyes.
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Theta waves. Usually found over the parietal and temporal regions. In children
between the ages two and five year’s theta waves are prominent. Rate—4-8 Hz.
Amplitude—100-150 microvolt.
Delta waves. It is postulated that the delta waves occur due to separation of the
cerebral cortex from the reticular activating system Rarely found in normal adults
during waking periods, but usually found during deep sleep and in serious organic
brain disease. In severe hypoxia and also in hypoglycemia 5-waves appear
frequently. In infancy it appears both during deep sleep and waking. Rate—
minimum 0,5-3,5 Hz or cycles per second, amplitude—variable 200~400
microvolt—high voltage slow-waves.
Physiological basis of EEG
Source of EEG. Originally it was of opinion that EEG waves are the summated
action potential of cortical cells discharging in a volume conductor. But present concept
is changed and it is due to current flow in the fluctuating dipoles formed on the dendrites
of the cortical cells and cell bodies. Cortical dendrites are the forest of densely units
placed in the superficial layers of the cerebral cortex. Dendrites are the sites of non propagated hyperpolarizing and hyperpolarizing local potential changes in the
excitatory and inhibitory axo-dendritic synapses. Dendrites are not the processes for
conduction and do not propagate action potentials. Action potentials are propagated
through the axonic terminals. When the excitatory axodendritic synapses are activated, current flow into and out in
between the cell body and axo-dendritic endings, causing a
wave-like potential fluctuation in the volume conductor.
(fig 51).
Thus EEG is the potential fluctuation in volume
conductor, but not the action potential and is conducted
through the axon only. Thus the dipole formed in between
the dendrites and the cell bodies fluctuates constantly due
Figure 51.
to the excitatory and inhibitory axo-dendritic synapses.
Mechanism of desynchxonisation and synchronisation. Definite pattern с a-rhythm
is due to synchronised activity of the many dendritic units. When the synchronised
activities of the dendritic unit are disturbed by incoming different sensory impulses, the
synchronized pattern of a-rhythm no longer persists and is replaced by desynchronised
pattern of irregular low voltage activity.
For the genesis of synchronised wave pattern, two factors are responsible, such as
synchronising effects of two parallel nerve fibres, and the influences of impulses from
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the thalamus and the brain stem. The characteristic feature of a wave indicates that the
activities of many dendritic units are synchronised. Large bilateral lesions in the nonspecific projection nuclei of the thalamus abolish the EEG synchrony.
Desynchronisation of EEG pattern with irregular low voltage acti v it y can be
produced by stimulating the specific sensory input up to the level of the midbrain. High
frequency stimulation of the reticular formation in the midbrain tegmentum and of the
non-specific projection nuclei of the thalamus desynchronises the EEG pattern.
II. Evoked cortical potentials
Evoked activity in the cerebral cortex is elicited by stimulating directly the cortical
surface (direct cortical response—DCR) or by stimulating the peripheral sense organ
like retina—by photostimulation, ear—by auditory click or the peripheral sensory nerve
endings or fibres. A characteristic response is seen in each case which is greatly
influenced by the effect of narcotics, drugs, physiological conditions like sleep, etc. The
waves consist of surface positive, followed by small negative and then by a larger more
prolonged positive deflection (fig 52).
Figure 52. Graphical representation showing response evoked in the contralateral sensory cortex
by stimulation of the sciatic nerve.
The first positive - negative waves sequence is the primary evoked response, the second
one is the diffuse secondary response.
Evoked and spontaneous electrical activities can be recorded directly from the
cerebral cortex through either extracellular or intracellular recording with the help of
microelectrodes (fig 53).
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Figure 53. Diagram showing discharge of Betz cells of the motor cortex stimulated by electrode at
the cortical surface. A – recording extracellularly and B-recording intracellularly.
III. Registration of electrical processes occurring in the separate nerve cells.
The study of the separate cells activity of various organs and tissues is of great
interest as it allows getting information of mechanisms and special features of agitation
and inhibition of these cells, the character of responses to different irritations, principles
of information coding in the CNS etc.
There are 2 methods of cells activity registration – intracellular and extracellular.
Extracellular method is methodically easier than intracellular as it presupposes the use
of comparatively thick (up to 50 – 100 mcm) glass and metal electrodes. The activity of
several neighboring cells is registered by such electrodes.
In case of intracellular activity registration microelectrodes filled with electrolyte
solution with the tip diameter of 0,5 – 1,0 mcm are usually used.
Method of surgical extirpations.
Method of surgical extirpations includes removal of different cerebral structures, their
mechanical destruction or coagulation by direct current anode. Functional cerebral
structures switching-off is achieved by their cooling or anodic polarization. The
disadvantage of this method is hemorrhage to the destruction zone and irritation by the
forming cicatricial tissue.
Stereotaxic method of irritative electrodes introduction to the certain cerebral points
through the trepanation skull foramina is widely used.
Stereotaxic technique.
For the electrodes introduction to the brain the animal’s head is fixed in the
stereotaxic apparatus by holders under anaesthetic. Holders are introduced into acoustic
passages and fixed with the lower edges of orbits or upper jaws.
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For electrodes orientation in the brain stereotaxic atlases are used for certain kinds of
animals. The atlases represent serial sections of the brain in the frontal, horizontal and
sagittal planes (fig 54).
Figure 54. Stereotaxic technique.
Counting is performed in zero planes. Frontal zero plane is in the external acoustic
passages. Sagittal zero plane is located along the sagittal suture.
The immersing electrode is fixed in the electrode clamp so as the electrode tip to
be located in the frontal zero plane. Then the clamp is moved forward and aside. At this
point of the skull the hole is perforated, and the electrode is immersed into the brain at
the certain depth. The additional control of electrodes tips localization is performed by
roentgenoscopy. There are stereotaxises with the special atlases for a human being use
in clinics.
Nowadays computer tomography is used for stereotaxic neurosurgery operations.
It allows using images of serial sections of brain for exact determination of coordinates
of any point in deep formations of brain. The stereotaxic neurosurgery together with
methods of temporary and continuous neuromodulations besides the reversible and
dosed influence at Parkinson's illness is also applied in treatment of serious stump and
neurogenic pains, essential tremor, difficult hyperkinesia, the spastic syndromes arising
at a cerebral palsy, injuries of spinal cord. The stereotaxic neurosurgery is used in
treatment of muscular dystonia, critical ischemia of extremities, the expressed spastic
stricture of distal segments of coronary arteries (H-syndrome), at serious posttraumatic
erectile dysfunction and defecation. It is used for restoration of spontaneous respiration,
in prophylaxis and treatment of decubitus at high injuries of spinal cord.
Exercise 1. Determination of individual profile of functional asymmetry
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Procedure.
Students test themselves or work in pairs “observer - probationer”. The right part of the
table 15 should be closed.
Table 15
I. Tests for motor asymmetry determination.
1. Interlacing of In right-handed persons the finger of the right hand is placed on
fingers
top, in left-handed ones– the finger of the left hand.
2.Crossing
of In right-handed persons the right hand is placed on top, in lefthands
handed - the left one.
“Napoleon’s
position”
3.
Test
of In right-handed persons the right hand performs percussion
applauding
movements, in left-handed – the left hand does.
4.Test of winding The leading hand performs winding, the passive one fixes clock
clock up
position.
5.Simultaneous
The quality of the drawing performed by the leading hand is
drawing (without higher. The quality of lines and completeness of picture are
visual control) of estimated.
the same figures
(a circle, a square,
a flower, a star)
by the right and
left hands
6. Test of hit The leading hand performs the test more exactly (declination is
exactness (eyes less than 10 cm).
are closed). The
paper target of
20x20 cm is
placed on the
table at a hand
distance.
The
tested
person
makes 10 points
with right and left
hands aiming at
the target center.
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7. Dinamometry
The force of each
hand is measured
three times. The
average value is
calculated.
8. To cross legs 4
times.
9. To compare the
size of thumb’s
nail bed of the
right and left
hands.
10. To measure
the step length by
the ruler, having
previously
marked 2 steps of
each leg on the
floor.
11.
Test
of
declination. The
tested
person
makes 8 steps
forward
with
closed eyes.
The leading hand exceeds the other hand by 2 kg. The difference
of less than 2 kg is an index of hands’ equality.
The leading leg is on top.
The nail bed of the leading hand is bigger. The equality indicates
“latent left-hander”.
The step of the leading leg is longer.
The declination to the left indicates prevalence of the right leg
and vice versa.
Coefficient of motor asymmetry is calculated in percentage by a formula:
Cr = [(Dr - Dl)/( Dr + Dl + Do)] x100%
Cr- coefficient asymmetry of the right hand,
Dr - number domination cases of right hand,
Dl - number domination cases of left hand,
Do - absent domination of any hand
Coefficient asymmetry (Cr) may be positive in 100% and less in right-hander and
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negative in left-hander. If the coefficient asymmetry more than +15 – it seemed to be
domination of right hand. If coefficient asymmetry less than -15 - it seemed to be
domination of left hand. If the figures situated between -15 and +15 - it is motor
symmetry.
Conclusions:
1. What are the leading hand and leg of the tested person?
2. What are the leading hand and leg of the group majority?
3. In what field of medicine and sport should the functional motor asymmetry be
considered?
II.
Tests for sensor asymmetry determination.
Table 16
1) Visual asymmetry.
1.Ask the tested person to wink.
The leading eye usually stays open.
2. The tested person shows how he looks He uses the leading eye.
into the microscope
3. The tested person holds in his hand a When the leading eye is closed
pen and compares it with vertical line in representation of the pen harsh displaces,
the distance of 3-5 m (the window or the when the not leader eye is closed the
door), then he closes his right and then displacement is little.
left eyes.
2) Acoustic asymmetry.
1.The tested person shows how he He holds on the telephone to the leading
usually uses the telephone
ear.
2. The tested person listening the watch The distance from leading ear is longer.
by each ear wary far from the ear
Conclusions:
1. What are the leading eye and ear of the tested person?
2. In what field of medicine and sport should the functional sensor system be
considered?
Lesson 2. Conditioned Reflexes. Conditioned Inhibitory Reflexes. Methods of
Making Reflexes and Methods of Formation of Conditioned Inhibitory Reflexes.
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Questions for studying.
1. The conditioned reflexes by Pavlov. The biologic role of the conditioned reflexes.
2. The classification of the conditioned reflexes.
3. The inhibition of the conditioned reflexes.
4. The mechanism of formation of the temporal connection between the nervous
centers.
5. Sleep. Slow wave sleep.
6. Paradoxical sleep.
7. Basic theories of sleep: role of the reticular activating system, neuronal centers,
transmitters and mechanisms that can cause sleep.
Reflex concept. Reflex classification.
A reflex is the response to a stimulus from the central nervous system. Reflexes can be:
congenital (unconditioned) and acquired (conditioned). Congenital reflexes (for
example, sucking) are inherent in the species as a whole, are inherited and do not require
special development. They are nutritious, sexual, protective, and adaptive. Conditioned
reflexes are developed throughout life. They are individual and not inherited.
Conditioned reflexes can be food, sexual, protective.
Also they can be:
- natural (developed on the basis of natural reinforcement) and artificial (developed on
the basis of artificial reinforcement)
- reflexes I, II and higher orders. The first order reflex is developed on the basis of
unconditional reflex. The second order reflex develops on the basis of the first order
reflex, etc. Higher-order reflexes are more difficult to develop. 2. Rules for the
development of conditioned reflexes.
Rules for the development of conditioned reflexes.
To develop a conditioned reflex, two stimuli are needed: 1) a conditioned or indifferent
stimulus (for example, light, bell, etc.). 2) unconditioned stimulus (food, electric current,
etc.)
- The conditioned stimulus should be biologically less significant than the
unconditioned stimulus.
- The conditioned stimulus should not be very strong
- The animal must be healthy, awake and free from other dominants (be hungry, have a
sexual dominant, etc.) (fig. 55).
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Figure 55. Making conditioned reflex.
Scheme and mechanisms of formation of temporary connections during the
development of conditioned reflexes.
A hungry dog has a dominant focus of excitation in the cerebral cortex and if we give
meat to s dog, a salivary reflex arises.
If we turn on a light bulb before eating, a focus of excitation also arises in the cerebral
cortex.
With the repeated combination of conditioned and unconditioned stimuli, (the light and
a food), a new conditioned reflex of salivation to light arises.
In this case, conditioned reflex connections between the cortical centers of the
conditioned stimulus and the cortical centers of the unconditioned stimulus are closed.
A temporary connection is formed (fig.56).
Figure 56. Mechanisms of formation of temporary connections in the cerebral cortex
during making condition reflex.
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Inhibition in HNA.
Inhibition in HNA is process as a result of conditioned reflexes are weakened up to a
total disappearance. It’s distinguished external (unconditioned) and internal
(conditioned) inhibition.
1. Unconditioned inhibition always accompanies excitement process, doesn`t demand
special elaboration and special conditions for realization. There are three types of
unconditioned inhibition.
- The dying – away inhibition. It arises at action of a new irritant which causes an
oriented reflex. This reflex inhibition is a conditioned reflex on the mechanism of
negative induction
- The constant inhibition arises on the disturbing influences (pain, for example).
- Ultra boundary or guarding inhibition. It arises at action of super strong
conditioned irritants and protects cortical cells from an overstrain.
2. Conditioned (internal) inhibition.
- Extinctive inhibition. –it appears in the absence of unconditional reinforcement.
- Differentiate inhibition. It provides distinction of similar signals, one of which
ceases to be supported.
- Conditioned inhibition. It arises at action of the additional irritant preceding a
conditioned irritant.
- The late inhibition (a reflex for delay). It allows including reflex reaction with a
delay after action of conditioned irritant.
Exercise 1. Making defensive conditioned reflex on human.
Purpose. To observe making defensive conditioned reflex on students. The response to
a stimulus that previously elicited little or no response, acquired by repeatedly pairing
the stimulus with another stimulus that normally does produce the response is called a
conditioned reflex. After the conditioned stimulus and unconditioned stimulus had
been paired a sufficient number of times, the conditioned stimulus produced the
response originally evoked only by the unconditioned stimulus. Moreover the
conditioned stimulus had to precede the unconditioned stimulus.
Equipment. Electrostimulator with electrodes, Ringer’s solution, lamp, watch.
Procedure.
1. The probationer put his fingers on electrodes.
2. Select the current’s force is sufficient to produce distinct defensive reflex. The
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conditioned stimulus must precede the unconditioned stimulus. The conditioned
stimulus must be lasted 2-3 sec.
3. In 2-3 sec the unconditioned stimulus must be added to the conditioned stimulus.
4. Both of stimuli must be followed after each other in a minute interval.
5. After 5 – 6 combinations of conditioned and unconditioned stimulus isolated using
of conditioned stimulus only elicit reflex withdrawal of the limb. This is conditioned
reflex.
Conclusions. After repeated using combination of conditioned and unconditioned
stimulus we have made the conditioned reflex at the probationer.
Lesson 3. Speciality of Human’s Mental Activity. Types of Highest Nervous
Activity. Analytical-synthesis Functions of Cerebral Cortex.
Questions for studying.
1. The types of temperament. Methods of studying of types of temperament.
2. Dynamic stereotype.
3. Language. Speech. Development of speech. Aphasia, classification of aphasias
(word-blindness, word-deafness, pure motor aphasia, agraphia, cortical aphasia).
4. Emotion. Different types of behavioral changes of emotion. Neural control of
emotion (hypothalamus, thalamus, cerebral cortex and limbic system).
5. Memory. Learning and Memory. Stages of memory (short-term memory, recent
memory, and long-term memory). Physiological basis of memory.
6. Reading. Writing.
7. Attention. Physiological mechanisms of attention.
Dynamic stereotype.
Dynamic stereotype is a complex of conditioned and unconditioned reflexes recorded
in memory. It is formed at frequent repetition in certain sequence of irritants. At the
same time the end of one reflex starts the following reflex. The dynamic stereotype plays
an important role in training.
Memory. Types and mechanisms of memory.
Memory is the ability of neurons to record, store and reproduce information. Types of
memory: short-term (seconds-hours), intermediate (hours-days) and long-term (daysyears) memory.
Memory mechanisms.
The basis of sensory memory is the trace potentials of a nerve impulse. The synaptic
basis of short-term (working) memory, possibly, is the long-term circulation of impulses
in the nerve circuits. The mechanisms of intermediate memory (consolidation) are
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associated with the activation of gene transcription and protein synthesis ("memory
proteins"). Long-term memory is associated with the mechanisms of activation of the
genome encoding proteins that improve synaptic transfer.
Types of Highest Nervous Activity.
The general classification of the types of higher nervous activity in humans and animals
was founded by I.P. Pavlov on the characteristics of arousal and inhibition. They are
assessed by strength (strong and weak), balance (balanced and unbalanced) and mobility
(agile and inert). The ratio of types of temperaments according to the classification of
Hippocrates and I.P. Pavlov (fig. 57):
- Melancholic. Weak nervous processes. Weak type according to I. Pavlov
- Choleric. Nervous processes are strong, mobile, unbalanced. The impetuous type
according to I. Pavlov
- Phlegmatic. Nervous processes are strong, balanced, but not very mobile. Inert type
according to I. Pavlov.
- Sanguine person. Nervous processes are strong, mobile, balanced. Strong type
according to I.P. Pavlov.
Figure 57. Four types of temperament
Exercise 1. Determination of the types of high nervous activity by psychological
test.
Procedure.
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1. Students test themselves or work in pairs “observer - probationer” with the list of the
characteristics of different temperaments (tab.17). It is necessary to put the sign “+”
in the corresponding column if this characteristic of temperament corresponds to
probationers. If this quality is absent in probationer’s character, it is necessary to put
the sign “-” in the corresponding column.
Characteristics
Choleric
Phlegmatic
Sanguine
of
(Ch)
(Phl)
(S)
temperament
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Sum of
Ach
Aphl
As
characteristics
2. Calculate sum of «+» in each column (Ach, Aphl, As, Am:
A= Ach + Aphl+ As + Am.
3. Calculate percentage for each temperament, where A is 100%.
For example:
Ach = 5, Aphl = 10, As = 15, Am = 5
A= Ac + Aph + As + Am = 5+10+15+5=35
If “35” is 100%, Ach = 14%, Aphl = 28%, As = 42% , Am = 14%.
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Table 17
Melancholic
(M)
Am
Conclusion: The probationer’s temperament is sanguine (42%).
Characteristics of temperament (types of high nervous activity).
Choleric:
1. Fussy, busting
2. Hot-tempered, irascibility
3. Sharpness, harshness in relationships
4. Resoluteness, initiativity
5. Stubbornness
6. Resourcefulness in dispute (argument)
7. Habit to work spurt
8. Tendency to risk
9. Not unforgiving
10. Fast and emotion speech
11. Intolerable to defects
12. Tendency to rood jokes
13. Expressiveness of facial expressions
14. Striving for new
15. Sharpness in moving
16. Persistency in achievement of goal
17. Tendency to sharp changing of mood
Phlegmatic:
1. Possibility to be quiet in any circumstances
2. Succession and thoroughness in affairs
3. Care and reasonableness
4. Possibility to wait
5. Silent
6. Quiet speech
7. Ability to finish the beginning affairs
8. Tendency not to waist force for nothing
9. Ability to have system in the work
10. Low impressionable to approval or reprimand
11. Not aggressive
12. Constancy of interests
13. Impossibility to begin and finish work fast
14. Equal attitude to everybody
15. Tidy in everything
16. Difficult adaptation to the new circumstances
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17. Self-discipline person
Sanguine:
1. Energy and efficiency
2. Tendency to overestimate myself
3. Ability to grasp the mining fast
4. Instability of interests
5. Easy attitude to failure
6. High adaptability to different circumstances
7. Enthusiasm in any new affair
8. Tendency to lose interest fast to some affairs
9. Unwillingness to do the same, everyday work
10. Sociable, lightness in relations with new people
11. High endurance, high ability to work
12. Loud, fast, emotional speech with
13. Ability to stay self-control in difficult circumstances
14. Ability to save always good mood
15. Ability to wake up and fall asleep fast
16. Not self-disciplined person
17. Tendency to superficiality opinion
Melancholic:
1. Tendency to get lost in new circumstances
2. Difficulties in relations with new people
3. Unbelief in self force
4. Easy attitude to loneliness
5. Tendency to retire into oneself
6. Fast fatigue
7. Silent speech
8. Tendency to adapt to character of interlocutor
9. Impressionability for tires
10. High impressionable to approval or reprimand
11. To make big demands of himself
12. Tendency to suspiciousness
13. Vulnerable, high sensitivity
14. Secretiveness, not sociability
15. Not activeness and timidity
16. Tendency to submit to one’s will
17. Striving for gaining sympathy
Observations, results and conclusion.
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THEME 6. SENSORY SYSTEM.
Lesson 1. The Special Senses. The Physiology of Visual System.
Questions for studying.
1. Types of sensory receptors.
2. Transduction of sensory stimuli into nerve impulses.
3. Receptor potentials and generator potentials.
4. Adaptation of receptors.
5. The optic system of the eye.
6. Physical principles of optics.
7. Anatomy and function of the structural elements of the retina.
8. Photochemistry of vision, color vision.
9. Neural organization of the retina.
10. Function of different types of cells.
11. The visual pathway from the eyes to the visual cortex.
12. Function of the primary visual cortex.
13. Visual acuity and the fields of vision.
14. Accommodation.
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Definition of the analyzer according to I.P. Pavlov. Functions of the analyzer.
The analyzer is a part of the nervous system that includes peripheral receptors, pathways
and sensory centers. The analyzer consists of three parts: receptor, conductive and
cortical (by Pavlov I.P.).
Functions of the analyzer:
1) Detection.
2) Distinction. The law of Weber and Fekhner works. “Intensity of feeling is directly
proportional to a logarithm of incentive power”.
3) Coding.
4) Transfer and transformation. Thus there is a restriction of surplus information and
allocation of essential signs of a signal.
5) Pattern of recognition. It is a final and the most difficult operation of the analyzer.
Thus there is a classification of an image, its reference to a class of objects which
the organism met earlier.
The visual system.
The structure of the eye is shown in the figure 58.
Figure 58. The structure of the eye.
The tissue of the sclera is continuous with the transparent cornea. Light passes through
the cornea to enter the anterior chamber of the eye. Light then passes through the central
round aperture called the pupil, which is surrounded by a pigmented muscle, known as
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the iris. After passing through the pupil, light enters the lens. Light from the lens that
passes through the vitreous body enters the neural layer, which contains photoreceptors,
at the back of the eye. This neural layer is called the retina. Light that passes through
the retina is absorbed by a darkly pigmented choroid layer underneath.
Receptor apparatus.
There are two types of photoreceptor neurons in retina: rods and cones. Both receptor
cell types contain pigment molecules that undergo dissociation in response to light, and
it is this photochemical reaction that eventually results in the production of action
potentials in the optic nerve.
Rods provide black-and-white vision under conditions of low light intensities, whereas
cones provide sharp color vision when light intensities are greater.
Fig. 59. Receptor apparatus
The photoreceptors - rods and cones - are activated when light produces a chemical
change in molecules of pigment contained within the membranous discs of the outer
segments of the receptor cells. Rods contain a purple pigment known as rhodopsin or
visual purpule.
When light falls on the retina, the rhodopsin passes rapidly through several stages.
A rod or cone contains many Na+ channels in the plasma membrane of its outer
segment, and in the dark, many of these channels are open. As a consequence, Na+
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continuously diffuses into the outer segment and across the narrow stalk to the inner
segment. This small flow of Na+ that occurs in the absence of light stimulation is called
the dark current, and it causes the membrane of a photoreceptor to be somewhat
depolarized in the dark.
The Na+ channels in the outer segment rapidly close in response to light, reducing the
dark current and causing the photoreceptor to hyperpolarize (fig. 60).
Fig. 60. Photochemical process in retina
Conductive part of the visual analyzer.
Axon of ganglion cells form an optic nerve (fig. 61). Optic nerves of both eyes partially
cross in the field of the skull basis. Further there is a visual tract.
The fibers of the visual tract go to the lateral geniculate bodies, the upper tubercles of
the quadruple, the thalamus, the suprachiasmatic nucleus of the hypothalamus and the
nucleus of the oculomotor nerve. From the upper tubercles quadruple fibers of the optic
tract fall into the pulvinar. Information comes from the thalamus are sent to the occipital
lobe of the brain.
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Fig. 61. Conduction and central parts of the visual analyzer
The visual acuity.
The visual acuity is the eye’s ability to differentiate two luminous points separately in
space. It is the sharpness to which the details and contours of objects are perceived. If a
series of black lines on a white paper is moved gradually far and far away from the
observer then a point will come when the observer fails to distinguish the objects on
such uniformly grey sheet of paper. Thus the resolving power of the eye is the angle
subtended at the eye by the spacing between the lines at the point where they are just
resolvable. The visual acuity must not be confused with the visual threshold. The visual
threshold is the minimal amount of light that elicits light sensation. The visual acuity is
usually defined in terms of minimum separable or resolution threshold, the shortest
distance, at which two lines will be perceived separately. The visual acuity depends
upon the sensitivity of retina to light, illumination of the surface, and ability to recognize
the distance of parallel rays. Visual acuity helps in determining shape form, outline and
minute details of the surroundings. It is expressed as the reciprocal of the angle
subtended at the nodal point of the eye—visual angle. The visual angle is generally one
minute (60 seconds) when the retinal images are separated by 4-5 µ. Visual acuity is
found to be: maximum at the fovea centralis where there is a large number of cones; and
there is minimum at the peripheral part of the retina where the number of cones is very
few. The visual acuity increases with monochromatic light. Errors of refraction reduce
the visual acuity.
Exercise 1. Determination of visual acuity with Rot’s apparatus and Sivcev’s table.
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Principle. In determining the visual acuity (acuteness of vision), figures such as a
broken circle Landolt’s “О” , Sivcev’s table with different letters, and Snellen's prong
“E”, printed black on a white ground and in graded sizes are applied (fig. 62). Landolt’s
“C” is almost universally used in scientific studies and is distinguishable from a circle
by a white gap; and the power to recognize the position of the gap, depends upon the
angle it subtends at the eye. The Landolt’s “C” can be rotated into eight separate
positions. The subject is seated at a distance of 5 meters and a letter is placed with the
gap of the “О” or the prong of the “E” turned to the right or left; he is asked to say in
which position the letter is directed. The width of the lines composing the letters and the
gap in the “С” or the spaces between the prongs of the “E”, subtend angles of different
degrees, depending on the size of the letter, when placed at a distance of 5 meters. The
width of the whole figure is five times thicker than its parts. By finding the smallest
letter whose position can be recognized the subject's visual acuity in terms of the visual
angle is ascertained. The maximum acuity measured with a Landolt “C” subtending 05 minute of arc, is about 2·1. In testing the visual acuity for fitting of glasses, Snellen's
test and Sivcev’s table is most commonly applied.
Figure 62. a –Snelen’s table;
b- Landolt’s broken circle “О”;
c- Sivcev table
Snellen's test type or Sivcev’s table (Russian variant). Clinically Snellen's test is
applied to measure the ability of the subject in discriminating different letters which are
constructed so that their details, subtend a known angle at a given distance from the eye.
This test type is devised upon the basis that two points or lines separated by a space
having a visual angle of 1 minute can be resolved by the average normal eye. This test
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comprises 10 or 12 rows of block letters printed in black upon a white background. The
rows of these letters are arranged in descending order of size from above down. The
width of the lines forming the letters of the first row subtends an angle of 1 minute at
50 meters from the eye, whereas that of the letters in the two to nine rows, have a visual
angle of 1 minute at 36, 24, 18, 12, 9, 6, 5, and 4 meters respectively. The top letter is
constructed in such a fashion that its details subtend 1 minute at 50 meters. The subject
stands at a distance of 5 meters and reads these letters with one eye closed. The acuteness
of vision is expressed, by a fraction of which the numerator is 5 (distance of 5 meters
from the letters) and the denominator is the distance at which the smallest letters can be
read by the eye.
V = d / D,
where V- visus, visual acuity;
d - is the distance at which the letters are seen by the tested person;
D- is the distance at which the letters are seen by the person with normal vision.
Snellen's test types of rectangular grid are also widely used. Each line of letters of a
different size is marked, with the distance in meters at which the small squares subtend
1 minute of arc. A normal individual at a distance of 5 meters distinguish the letters of
the 5 meter line and his visual acuity will be 5/5 = 1. Subjects, having defective vision,
distinguish letters standing 50 meters from a well-lit chart then his acuity will be 5/50
=0,1. There is a number near each row, which means the distance at which the letters
are seen by the person with normal vision (in meters). At right side is shown the vision
acuity, which is calculated by the formula.
Equipment. Rot’s apparatus, shield (fig.63).
Rot’s apparatus is a box with mirror sidewalls for reflection of light of a lamp and the
lamp lighting the Sivcev’s table with different letters of different size on the back wall
of the box.
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Figure 63. Rot’s apparatus with Sivcev’s table.
Procedure:
1. Patient seats on the chair in the distance from the Rot’s apparatus (5 meters).
2. First close by shield the right, and then close the left eye.
3. Say the pointed letters on the table.
4. Define the visual acuity each other.
5. Calculate the visual acuity by formula and make conclusion.
For example, my visual acuity or visus equals = 1.0.
Observations, results and conclusion.
Exercise 2. Determination of visual fields (or range of vision).
Definition. On looking strait ahead, with the eyeball fixed, that part of the external
world which can be seen with each eye is called the visual field of that eye.
Extent. Laterally, it extends up to 1040 i.e., behind the horizontal plane on the nasal
side about 650. In front there is a cone-shaped area in which the two fields overlap and
enjoy binocular vision. The visual field for blue, red and green are progressively smaller
(fig.64).
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Figure 64. Visual fields of left eye for white, blue, red and green colors.
The map of the visual field (Perimetry) is determined by using Forster’s perimeter
(fig.65). It consists of a metal piece shaped like an arc of a circle, the centre of which is
always marked by a fixed pointer attached to the base of the instrument. The subject’s
head is supported in the chinrest and the eye to be examined is placed very close to the
metal point indicating the center of arc. The other eye is covered. An index mark, white
in color with the diameter of about 2 mm, is made to slide along the arc to find the limits
of visual field in that meridian. The index mark can be blue, red, or green to find out the
corresponding color field. The arc can be rotated around a horizontal axis through a full
circle, and at each new situation the test is repeated to find out the field in that meridian.
These results when plotted give the visual field. During special diseases, also lesions of
optic pathway, visual fields are various: the local part of visual field or half of it can
disappear (scotoma, hemianopsia).
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Figure 65. Determination of visual fields with Forster’s perimeter.
Equipment. Forester’s perimeter, shield.
Procedure:
1. Patient closes by a shield one eye, fixes the view on white point, and he doesn’t
move his eye.
2. Observer takes a special wand with white index mark and start moving it from
peripheral side of arc to its center.
3. Patient has to say when he can see the wand by peripheral vision and to define
the color of mark.
4. Observer notes a value on a-degree scale of arc and draws the results in the special
blank, paper with concentric circle lines and meridian lines over them (fig. 43). It
is the normal visual field for right or left eye on the blank (trait lines).
5. Connect the obtained points and compare the area between the normal and taken
results.
Observations, results and conclusion.
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Lesson 2. The Sense of Hearing.
The questions for studying:
1. Structure of the ear, Its parts.
2. Structures and functions of the external ear and middle ear.
3. The internal ear. A structure of cochlea.
4. The organ of Corti – structure and function.
5. Conduction of sound from the tympanic membrane to the cochlea.
6. Excitation of the hair cells. Hair cell Receptor Potential and excitation of
auditory nerve fibers.
7. Auditory Pathways
8. Function of the Cerebral cortex in hearing.
9. Deafness. Types of Deafness.
Deafness
The primary acoustic centre is in the temporal lobe of the cerebrum. Removal of both
temporal lobe is followed by complete deafness and of one temporal lobe is followed
by impairment of hearing. This holds that some fibres from each ear cross at some point
in their afferent pathways and terminate in the opposite cortex.
Deafness may be of two types: (1) conductive deafness, and (2) nerve deafness.
1.
In conductive deafness there is interference with the passage of sound waves
through the external ear and middle ear.
(1) External ear obstructions— the conductive deafness occurs due to entrance of
foreign bodies, or due to hard or dry wax in the external ear. The damage or perforation
of tympanic membrane may be the cause of failure of conduction.
(2) Middle ear disease — any condition which prevents the normal functioning of the
ossicles. This condition is frequently observed in nasal catarrh, otosclerosis, etc.
2. The nerve deafness is due to loss of function of organ of Corti and also due to
interference of transmission of impulses by the auditory nerve. The temporary nerve
deafness occurs after exposure to a very loud sound. The main causes are:
1) Due to bacterial or viral infection as in Meningitis in children.
2) Due to acoustic trauma as in boiler-makers.
3) Due to toxic action of the drugs - some antibiotics (streptomycin, kanamycin),
quinine, measles, etc.
4) Due to pressure of a tumour at the junction of cerebellum and pons.
The nerve deafness is also found in Meniere's syndrome which occurs in adult and is
accompanied by vertigo. This is due to increased hydrostatic pressure in the endolymph.
There may be also hereditary nerve deafness.
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1. Auditory analyzer. Structure. Functions.
Auditory analyzer is a sensory system that perceives vibrations of the external and
internal environment (frequency from 20 hertz to 20 kilohertz) and forms sound
sensations. Auditory analyzer includes the auricle, external acoustic canal, middle ear
and inner ear (fig.66).
Figure 66. Auditory analyzer.
In the inner ear, the bony canal of the cochlea divides two membranes into three canals:
high, lower, and middle. Endolymph fills the middle canal. The organ of Corti is in the
middle channel.
This organ includes the cochlear hair receptor cells and the tectorial membrane.
The electric phenomena in a snail:
- Receptor potential. It is connected with bending of stereocillia at action of a
sound.
- Cochlear microphone potential arises at action of a sound and is generated by
external hair cells.
The emergence of excitation in the receptor of the auditory analyzer. Stereocilia are
bent by sound. The greater the displacement of the basilar membrane and the bending
of the stereocilia, the greater the amount of transmitter released by the hair cell, and
therefore the greater the generator potential produced in the sensory neuron. A
greater bending will result in a higher frequency of action potentials, which will be
perceived as a louder sound (fig.67).
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Figure 67. Organ of Corti.
Conductive section of the auditory analyzer. Sensory neurons in the vestibulocochlear
nerve (VIII) synapse with neurons in the medulla oblongata that project to the inferior
colliculus of the midbrain. Neurons in this area, in turn, project to the thalamus, which
sends axons to the auditory cortex of the temporal lobe.
Cortical section of the auditory analyzer. The primary auditory cortex is the 41st field
of the Heschl gyrus and the 42nd field of the superior temporal cortex. Provides a sense
of tones, noises, sounds. The secondary auditory cortex is the 22nd field of the superior
temporal cortex. This provides an understanding of the sequence of tones.
Exercise 1. Determination of auditory acuity.
Determination of auditory acuity is finding out of patient’s ability to distinguish silent
whisper speech. The person with normal hearing perceives speech by whisper at a
distance of 4-5 meters.
Equipment. Tape-measure.
Procedure:
1. Patient sits back to observer at a distance of 5-6 meters. One of patient’s ears is closed;
another is opened and directed to the observer.
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2. Observer names in a low voice different numbers.
3. Patient should repeat heard words. If he does not hear a word then the observer
approaches gradually to the patient until he starts repeating the pronounced words
correctly.
Observations, results and conclusion.
Test for deafness.
Principle. Rinne’s test. The base of a vibrating tuning fork is placed over the mastoid
process of the subject. When the sound fades away (bone-conduction ceases) the prongs
of the fork are brought towards the external auditory canal. If there is no abnormality in
the tympanic membrane and ear ossicles, the air-conducted sound is heard for a longer
period by the subject and the test is said to be positive. If the sound is heard longer by
bone-conduction the test is said to be negative, and indicates conductive deafness (fig.68
c). In case of internal ear disease affecting the nervous conduction the test is said to be
positive and indicates perceptive deafness (fig.68 b).
Weber’s test. The base of a vibrating tuning fork is placed over the midline of
the vertex of the subject (fig.68 a). The sound is heard equally in both ears. In unilateral
middle ear disease affecting the conductive system, the sound is better heard in the
diseased ear and Weber's test is said to be positive. In case of unilateral internal ear
disease affecting the nervous conduction the sound is better heard in the normal ear.
Rinne's and Weber's tests help to differentiate middle ear or conductive deafness
from internal ear or perceptive deafness.
Figure 68. a. The Weber test furnishes only a comparison of two ears. If a subject has nerve deafness
which is worse in one ear than the other, the tone will be heard best in the better ear. The tone will be
heard in the poorer ear if the subject has asymmetric conductive deafness.
b. Tone heard longer by air conduction - Rinne positive.
c. Tone heard longer by bone conduction - Rinne negative.
Exercise 2. Determination of bone conductivity of sound.
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The Weber’s test is test of bone conductivity. The research of bone conductivity of a
sound allows differentiate defeats of middle and internal ears.
Equipment. Set of tuning forks, hammer.
Procedure.
1. Take a tuning fork С128 and strike it with a hammer.
2. Put the base of a sounding tuning fork over the midline of the vertex of the patient
(put it to parietal bone in the middle of the patient’s head). In norm the patient hears a
sound of a tuning fork equally with both ears.
3. The patient closes one ear with a wadded ball (simulating defeat of a middle ear): the
sound in opened ear will be stronger. At defeat of an internal ear the sensation of a sound
increases in a healthy ear.
Observations, results and conclusion.
Exercise 3. Determination of bone and air conductivity of sound.
Principle. Air conductivity of a sound is provided with distribution of a sound wave
through a hearing aid of an external and middle ear. Bone conductivity of a sound is a
transfer of sound waves through bones of a skull to an internal ear. For comparison of
air- and bone- conductivity of a sound carry out Rinne’s test.
Equipment. Set of tuning forks, hammer.
Procedure:
The basis of a vibrating tuning fork put to a shoot of a temporal bone. Mark time of
sounding of a tuning fork. At disappearance of a sound a tuning fork bring to an external
ear (distance of a tuning fork from external auditory canal equally 0.5 - 1 sm). The
patient again hears a sound. Define time during which the sound is audible.
Compare time of air- and bone- conductivity. In norm time of air conductivity in 2
times is longer, than time of bone conductivity.
Observations, results and conclusion.
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