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METHODICAL INSTRUCTIONS
and notes for practical studies of Normal Physiology
"COMMON PHYSIOLOGY OF EXITABLE TISSUE. NEURAL AND
HUMORAL REGULATION OF ORGANISM
Methodical Instructions to Lesson 1 for Students
Themes:
1. PHYSIOLOGY IS THE THEORETICAL BASES OF MEDICINE.
2. BIOELECTRICAL PHENOMENA IN NERVE CELLS.
Aim: To know the common characteristic of physiology, method of physiology,
history of it development. To know the analyze the mechanisms of beginning the
resting membrane potential and membrane potential, methods of their registration
in nerves and muscles.
Professional Motivation: The knowledge of physiology is necessary for future
physicians to decision the normal and pathological processes. The knowledge of
resting membrane potential and membrane potential, methods of their registration
in nerves and muscles is necessary for future physicians to value the functional
condition of excitable tissues.
Basic Level:
1. History of medicine (History of medicine Course)
2. Medical apparatus. Installing of electrical impulses (Physics Course)
3. Structure of nerves cells, their membranes (Biology Course)
4. Anatomy of nerves (Anatomy Course)
Students’ Practical Activities:
Theme 1
Student must become acquainted with
A. The main notion of physiology (After-depolarisation, after-hyperpolarisation,
antiport, chemical mediator, electrical synapses, exitation, firing level, inhibition,
latent period, local responce, overshoot, period of latent addition, postsynaptic cell,
presynaptic cell, refractory period, resting membrane potential, saltatory
conduction, spike, stimulator, subnormal period, supernormal period, symport,
synapses), find it in book and note in the notebook.
B. The functional diagnostic apparatuses (All apparatuses, which are used in
physiological investigation, are divosed into 2 main groups: 1) apparatus for
irritation of biological structure; 2) apparatus for register of physiological
processes which are reflect different function. The stimulators (such as electric
stimulators) and irritable electrodes (device which help to pass stimulus on the
object which had stimulated) belong to the first group of apparatus. The registers,
corresponding electrodes (device which transform nonelectrical processes on
electrical) belong to the second group of apparatus.)
C. The scheme of keeping a protocols of practical units
1. Number of protocol, date
2. Theme of unit
3. Title of students’ practical activities
4. Method of students’ practical activities fulfillment
5. Receiving results
6. Conclusion
Theme 2
Definition of speed conduction of excitation by moving nerve
To establish stimulating electrodes over the nervus ulnaris more medial to
processus ulnaris. The leading electrodes place over the abducens muscle of fifth
finger. Inflict the upper threshold stimulus.
On the electromyograph‘s screen to definite the time from moment of infliction
of stimulus to moment of origin the active potential (latent period) – t1. To carry
stimulating electrodes in distant place and definite this latent period – t2. The
results, which receiving on the electromyograph‘s screen represent in your exercise
book.
To measure the distance between the place of stimulating electrodes – S.
The speed‘s conduction of excitation which are moving by nerve determine
according to the formula: V=S : (t1-t2) (m/s).
In conclusion define whether the speed is within physiology norm. If not, than
explain the reason of this phenomena.
Students’ Independent Study Program
Objectives for Students’ Independent Studies
You should prepare for the practical class using the existing textbooks and lectures.
Special attention should be paid to the following:
Theme 1
1. Common characteristic of physiology
a) Defining of “physiology” notion (Physiology is the science about the
regularities of organisms‘ vital activity in connection with the external
environment.)
b) Tasks of physiological subjects (A deep studying of the mechanisms of
vital activity of health man with the matter of expose the causes and characters‘
breaches of this mechanisms in different diseases.)
c) Connection of physiology with other sciences (Connection of physiology
with anatomy course – the names, localization, functions of nerves, muscles,
bones, vessels, inner organs, endocrine glands; with histology – the structure of
nerves, muscles, bones, vessels, inner organs, endocrine glands; with chemistry –
osmotic and oncotic pressure, gradient of concentration, with physics – electric
conductivity, with biology – blood groups inheritance. This is the connection of
physiology with the subjects which was studied. The physiology is necessary for
pathologic physiology, pathologic anatomy, surgery, obstetrics, therapeutics.)
2. Method of physiology
a) Observation (This is the method in which the scientists don‘t mix in course
of vital processes. They only make use of vision and description of all changes. On
the base of this changes they make conclusions.)
b) Experiment (There are two kinds of experiments: acute and chronic. Acute
experiment was doing with the helps of anesthesia. It may be accompanied by cut
off the nerves, introduction the different substances. The chronic experiment was
doing in vital animals, for example, after the acute experiment scientists can used
the observation.)
c) Examination (This is the method of examine the patient with different
diseases, for example, with using the different apparatuses.)
d) Simulation (We can simulation different processes as a laboratory
simulation or realistic simulation, for example, apparatus of artificial kidney or
apparatus of artificial circulation. It may be the simulation the different processes
by means of computers.)
3. History of physiology development
a) Till 17 century (The first medicine used the knowledge about function of
health and ill person and animal, which was based on the observation method. This
summarizing of receiving results was doing by Hippocrates, Gallen, Aristotel, Ibn
Sina (Avicenna). One of the doctor was Akmean. He come to the conclusion that
brain is the organ of consciousness and answer for memory, thought, filling.
Empedocl determined that the breathing are doing not only by nose and mouth, but
through skin too. Pracsagor distinguished the arterial and venous vessels, but it
thought that they have air. Gallen considered that arteries had blood, established
the knowledge about the breathing, described the nerves.)
b) In 17-18 centuris (Garvey in 1628 published the work about the small and
big circles of blood circulation and about the heart as a engine of blood. Decart
was the author of the first text-book “About the Man”, developed the theory of
pain, hunger, thirst, digestion, vision, memory. The high of his physiology
investigation was the description of the organism‘s reaction on the external
irritations. Prokhaska considered that the reflex act may arise in internal and
external stimulus. Levenguk and Malpigy described the capillaries. This
development widen the vision on blood circulation. Discovering Azelly and
Bartolini lymphatic vessels maintain the lymph circulation. Galvani put the bases
of electric physiology.)
c) From 19 century to our days (In 19 century physiology separated of
anatomy and became the independent science. Majandi studied the physiology of
nerves system. Bernar studied the physiology mechanisms of development of
digestive juice and their digestion properties, the role of liver in supporting the
sugar level in blood, meaning of constant of pupils‘ internal surrounding. Yung
worked out the three component theory of color perception. Gelmgolths developed
this theory and creation the theory of hear perception. Phylomaphytsky worked out
the theory of cyclic functioning of nerves system. Phylomaphytsky and Basov
worked the operation of suturing the gastric fistula on dogs. Phylomaphytsky and
Pirogov worked the method of anesthesia intravenous. Gering worked out the
theory of the color vision. Gering and Braier described the reflex of nervus vagus,
which control the breathing. Boydich formulated the “all or none” low, which say
that cardiac muscle can contract in full or noncontract. In 1846 Ludvig described
the theory of uropoiesis. Kennon created the doctrine about homeostasis. G.Selye
studied the stress-syndrome.)
d) Standing of physiology in Ukraine (In year 1593 was opened the first high
medical school near Lviv – Zamoiska academy. In year 1594 this school became
the university and it has given the doctor degree. In 1661 was opened the Lviv
University with the medical faculty. In 1805 was opened the Charkiv University
with the medical faculty. On this the medical faculty studied Danilevsky, who
published the important work about the influence of brain on blood circulation and
breathing, the text-book from physiology, he was the one science in the world, who
register bioelectrical phenomenon of dogs‘ brain. In September 1842 developed the
chair of physiology of health people in the medical faculty of Kiev University. In
1842 Valter opened the nerves of vessel constriction and showed that its is the
sympathetic. Leontovich was the first in the world who described the nerves cells
in the peripheral plexuses and lead that peripheral nerves plexuses resume during
the life, worked out the original method of staining which permit study of synapses
in nerves system and come to the conclusion that it is the physiological apparatuses
between neuronal connection. In 1913 Pravdich-Neminsky register
electroencephalogramm in experiment. Voroncov created the common theory
about the unity of main physiology processes excitement and inhibition. Bogach
was the first who established the regulatory influences of hypothalamus on the
pancreatic juice secretion. . In 1865 was opened the Odessa University. Sechenov
opened the inhibition in central nerves system. In 1863 Sechenov published the
book “Reflexes of brain".)
Key words and phrases: After-depolarisation, after-hyperpolarisation,
antiport, chemical mediator, electrical synapses, exitation, firing level, inhibition,
latent period, local responce, overshoot, period of latent addition, postsynaptic cell,
presynaptic cell, refractory period, resting membrane potential, saltatory
conduction, spike, stimulator, subnormal period, supernormal period, symport,
synapses, apparatus for irritation of biological structure; apparatus for register of
physiological processes, observation, experiment, examination, modeling
Theme 2
1. Resting membrane potential
a) Common characteristic (There is a potential difference across the
membranes of most if not all cells, with the inside of the cells negative to the
exterior. By convention, this resting membrane potential (steady potential) is
written with a minus sign, signifying that the inside is negative relative to the
exterior. Its magnitude vanes considerably from tissue to tissue, ranging from -9 to
–100 mV. When 2 electrodes are connected through a suitable amplifier to a CRO
and placed on the surface of a single axon, no potential difference is observed.
However, if one electrode is inserted into the interior of the cell, a constant
potential difference is observed, with the inside negative relative to the outside of
the cell at rest. This resting membrane potential is found in almost all cells. In
neurons, it is usually about –70 mV.)
b) Mechanism of development (There are two kind of ion’s transport: active
and passive. Active transport is doing due to the energy of ATP. The sodiumpotassium pump responsible for the coupled active transport of Na+ out of cells and
K+ into cells is a unique protein in the cell membrane. This protein is also an
adenosine triphosphatase, ie, an enzyme that catalyzes the hydrolysis of ATP to
adenosine diphosphate (ADP), and it is activated by Na+ and K+. Consequently, it
is known as sodium-potassium-activated adenosine triphosphatase (Na+-K+
ATPase). The ATP provides the energy for transport. The pump extrudes three Na +
from the cell for each two K+ it takes into the cell, ie, it has a coupling ratio of 3/2.
Its activity is inhibited by ouabain and related digitalis glycosides used in the
treatment of heart failure. It is made up of two  subunits, each with a molecular
weight of about 95,000, and two  subunits, each with a molecular weight of about
40,000. Separation of the subunits leads to loss of ATPase activity. The  subunits
contain binding sites for ATP and ouabain, whereas the  subunits are
glycoproteins. Application of ATP by micropipette to the inside of the membrane
increases transport, whereas application of ATP to the outside of the membrane has
no effect. Conversely, ouabain inhibits transport when applied to the outside but
not to the inside of the membrane. Consequently, the  subunits must extend
through the cell membrane. The protein could exist in 2 conformational states. In
one, three Na+ bind to sites accessible only from the inside of the membrane. This
triggers hydrolysis of ATP, and the protein changes its conformation so that the
three Na+ are extruded into the ECP. In the second conformation, two K+ bind to
sites accessible only from the outside of the membrane. This triggers a return to the
original conformation while extruding two K+ into the interior of the cell. It
appears that Na+ binding is associated with phosphorylation of the protein and K +
binding with dephosphorylation.)
2. The origin of excitation
a) Characteristic of experimental stimulus (For the force it divided on the
under threshold, threshold and upper threshold.)
b) Local answer, critical range of depolarization (Local answer is arised only
on under threshold stimulus. Critical range of depolarization is the point from
which the action membrane potential can develop.)
c) Genesis of the membrane potential (The stimulus artifact is followed by an
isopotential interval (latent period) that ends with the next potential change and
corresponds to the time it takes the impulse to travel along the axon from the site
of stimulation to the recording electrodes. Its duration is proportionate to the
distance between the stimulating and recording electrodes and the speed of
conduction of the axon. If the duration of the latent period and the distance
between the electrodes are known, the speed of conduction in the axon can be
calculated. For example, assume that the distance between the cathode stimulating
electrode and the exterior electrode is 4 cm. The cathode is normally the
stimulating electrode. If the latent period is 2 ms long, the speed of conduction is 4
cm/2 ms, or 20 m/s.
The first manifestation of the approaching impulse is a beginning
depolarization of the membrane. After an initial 15 mV of depolarization, the rate
of depolarization increases. The point at which this change in rate occurs is called
the firing level. Thereafter, the tracing on the oscilloscope rapidly reaches and
overshoots the isopotential (zero potential) line to approximately +35 mV. It then
reverses and falls rapidly toward the resting level. When repolarization is about 70
% completed, the rate of repolarization decreases and the tracing approaches the
resting level more slowly. The sharp rise and rapid fall are the spike potential of
the axon, and the slower fall at the end of the process is the after-depolarization.
After reaching the previous resting level, the tracing overshoots slightly in the
hyperpolarizing direction to form the small but prolonged after-hyperpolarization.
The after-depolarization is sometimes called the negative after-potential and the
after-hyperpolarization the positive after-potential, but the terms are now rarely
used. The whole sequence of potential changes is called the action potential. It is a
monophasic action potential because it is primarily in one direction. Before
electrodes could be inserted in the axons, the response was approximated by
recording between an electrode on intact membrane and an electrode on an area of
nerve that had been damaged by crushing, destroying the integrity of the
membrane. The potential difference between an intact area and such a damaged
area is called a demarcation potential.)
d) Changing of excitability in the time of excitation (During the action
potential as well as during catelectrotonic and anelectrotonic potentials and the
local response, there are changes in the threshold of the neuron to stimulation.
Hyperpolarizing anelectrotonic responses elevate the threshold and catelectrotonic
potentials lower it as they move the membrane potential closer to the firing level.
During the local response the threshold is also lowered, but during the rising and
much of the falling phases of the spike potential the neuron is refractory to
stimulation. This refractory period is divided into an absolute refractory period,
corresponding to the period from the time the firing level is reached until
repolarization is about one-third complete; and a relative refractory period, lasting
from this point to the start of after-depolarization. During the absolute refractory
period no stimulus, no matter how strong, will excite the nerve, but during the
relative refractory period stronger than normal stimuli can cause excitation. During
after-depolarization the threshold is again decreased, and during afterhyperpolarization it is increased. These changes in threshold are correlated with the
phases of the action potential.)
3. Receptor potential (Stimulation of dendrites of nerves cells lead to oscillation of
resting membrane potential. This changes called receptor potential. Duration of
receptor potential correspond to duration of stimulation. Receptor potential cause
by increasing of nerves permeability of dendrites membrane. Receptor potential
lead to axon hillock. Spreading of receptor potential depend on diameter of
dendrites, resistance of cytoplasm and resistance of cell membrane.
4. Carrying of excitation by axons
a) Condition of carrying (1. Anatomic integrity of nerve‘s filament. 2.
Physiological full value.)
b) Laws of carrying (1. Double-sided conduction. 2. Isolated of conducting. 3.
Conducting of excitation without attenuation.)
c) Carrying in myelinated nerves (In myelin filaments conducting of excitation
is doing from node of Ranvier to node of Ranvier.)
d) Carrying in nonmyelinated nerves (In nonmyelin filaments conducting of
excitation is doing uninterrupted.)
Key words and phrases: potential difference, excitability, excitation, local
response, refractory period, after-depolarization, membrane potential, stimulation,
after-hyperpolarization, absolute refractory period, relative refractory period, local
answer, critical range of depolarization, resting membrane potential, zero potential,
spike potential, period of latent addition, supernormal period, subnormal period,
firing level, propagated action potential, axon hillock
Students must know:
Theme 1
1. Common characteristic of physiology
2. Method of physiology
3. History of physiology development
4. Main notion of physiology
Theme 2
1. Structure of cell membrane
2. Structure of nerves
3. Bioelectrical condition of cell membrane
4. Origin of excitement and stimulate of excitability
Students should be able to:
Theme 1
1. To define the type of functional diagnostic apparatuses
2. To keep protocols of practical units.
Theme 2
1. To estimate bioelectrical phenomenon in excitable tissues
2. To master the techniques of biopotential lead
Tests and Assignments for Self-assessment
Multiple Choice.
Choose the correct answer/statement:
Theme 1
1. What kind of physiological method doing only on peoples?
a) Observation; b) Acute experiment; c) Chronic experiment; d) Examination;
e) Modelling
2. What kind of physiological method doing only on animals with aneasthesia?
a) Observation; b) Acute experiment; c) Chronic experiment; d) Examination;
e) Modelling
3. What kind of physiological methods doing only on animals without aneasthesia?
a) Observation, acute experiment; b) Acute experiment, chronic experiment; c)
Chronic experiment, observation; d) Examination, acute experiment; e)
Modelling, chronic experiment
4. Who was study the breathing?
a) Gallen, Empedocl; b) Hypocrat, Decart; c) Empedocl, Garvey; d) Akmean,
Levenguk; e) Magandy, Galvany
5. Who was study the vessels structure?
a) Hypocrat, Empedocl, Aristotel; b) Decart, Gallen, Levenguk; c) Galvany,
Magandy, Aristotel; d) Pracsagor, Gallen, Garvey; e) Hypocrat, Akmean, Aristotel
Real-life situations to be solved:
1. Patient D. went to you in therapeutic unit with some complains. What kind of
physiological method do you use?
2. You want to study the changing of breathing in the different condition of
atmospheric pressure. What kind of physiological method do you use?
Answers for the Self-Control
1. d; 2. b; 3. c; 4. a; 5. d
1 real-life situation – Examination and observation. 2 real-life situation – chronic
experiment on animals, may be rats, rabbits or dogs.
Theme 2
1. In the nerves cells during the resting membrane potential:
a) Na+ and K+ go into the cells; b) Na+ and K+ go from the cells; c) Na+ go into
the cells, K+ go from the cells; d) K+ go into the cells, Na+ go from the cells; e)
Na+ and K+ don‘t move
2. In the nerves cells during the local response:
a) Na+ and K+ go into the cells; b) Na+ and K+ go from the cells; c) Na+ go into
the cells, K+ go from the cells; d) K+ go into the cells, Na+ go from the cells; e)
Na+ go into the cells
3. In the nerves cells during the depolarization:
a) Na+ intensively go into the cells; b) K+ intensively go from the cells; c) Na+
go into the cells, K+ go from the cells; d) K+ go into the cells, Na+ go from the
cells; e) Na+ and K+ go into the cells
4. In the nerves cells during the repolarization:
a) Na+ intensively go into the cells; b) K+ intensively go from the cells; c) Na+
go into the cells, K+ go from the cells; d) K+ go into the cells, Na+ go from the
cells; e) Na+ and K+ go into the cells
5. In the nerves cells during the spike:
a) Na+ and K+ go into the cells; b) Na+ intensively go into the cells; c) Na+ and
K+ go from the cells; d) K+ intensively go from the cells; e) Na+ and K+ go
from the cells
6. In the nerves cells during the after-hyperpolarization:
a) Na+ intensively go into the cells; b) Na+ go into the cells, K+ go from the
cells; c) K+ go into the cells, Na+ go from the cells; d) Na+ and K+ go into the
cells; e) Na+ and K+ go from the cells
Real-life situations to be solved:
1. Firing level of membrane cell increased from -60 mV to -50 mV. What and
why changing excitability of cell?
2. Stimulus caused depolarization of the membrane cell, but the excitability of
the cell decreased. What is the cause of this change?
Answers for the Self-Control
1. c; 2. e; 3. a; 4. b; 5. e; 6. c
1 real-life situation – 1. Excitability of cell decrease, because firing potential of its
membrane increase. 2. The excitability of the cell decreased during the increasing
of firing level.
References:
1. Review of Medical Physiology // W.F.Ganong. – Twentieth edition, 2001. – P.
1-12. 49-58.
2. Textbook of Medical Physiology // A.C.Guyton, J.E.Hall. – Tenth edition, 2002.
– P. 2-9. 52-65.
Methodical Instructions to Lesson 2 for Students
Themes:
1. PHYSIOLOGY OF SYNAPSES.
2. PHYSIOLOGY OF CONNECTION BETWEEN THE NEURONS.
3. ELECTROPHYSIOLOGICAL PHENOMENA IN MUSCLE CELLS.
4. PHYSIOLOGY OF SPINAL CORD.
Aim: To know the peculiarities mechanisms of transmission‘s excitation through
the synapses in the skeletal and smooth muscles. To know the functioning
peculiarities of nervous system. To know the function, physiological properties and
processes in skeletal, smooth and cardiac muscles. To know functions, reflectory
activity, ascendens and descendens ways of spinal cord, to provoke and estimate
tendinous and dermal reflex of spinal cord.
Professional Motivation: The knowledge of the peculiarities mechanisms of
transmission‘s excitation through the synapses in the skeletal and smooth muscles
is necessary for future physicians for nomination medicine of synaptic effect. The
knowledge of the functioning peculiarities of nervous system, peculiarities of
excitement transmition in neural chains, inhibition, reflexes is necessary for future
physicians for understanding the principles of nervous system working. The
knowledge of functions, physiological properties and processes in skeletal, smooth
and cardiac muscles is necessary for future physicians to evaluate their functional
condition. The knowledge of functions of spinal cord is necessary for future
physicians to analyse the mechanisms` status of segmental regulation of
organism’s functions in norm and pathology, in clinical diagnosis, in preventive
and therapeutic measures.
Basic Level:
1. Structure of smooth muscle. Structure of skeletal muscle. Anatomy of spinal
cord (Anatomy Course).
2. Structure of nervous and neuroglial cells. Ultrastructure of muscles.
Ultrastructure of spinal cord (Histology Course)
3. Structure of reflector arc (Biology Course)
4. Bioelectrical potential (Physic Course)
5. Anatomy of muscle (Anatomy Course)
Students’ Practical Activities:
Theme 1
Evaluation of neuro-muscular transmission
To establish stimulating electrodes on the forearm (antebrachium) over the
nervus ulnaris. The leading electrodes place over the muscle flexion wrist ulnar.
Inflict the upper threshold stimulus with the gradual increasing of frequency to 70
impulses per second. On the electromyograph‘s screen look after the changing of
amplitude of active membrane potential. The results, which receiving on the
electromyograph‘s screen represent in your exercise book.
In conclusion evaluate the condition of neuro-muscular transmission. To
explain the changing of active membrane potential when the frequency of stimulus
increased.
Theme 2
Space summation of under threshold stimulation
To establish stimulating electrodes on the project of m. flexor carpi radialis in
the middle third of antebrachii with the common square 1,2 sm2. To establish level
of threshold stimulus, which elicit prolonged contraction of muscle.
After that on this muscle put the electrodes with common square 4,0 sm2.
Inflict the under threshold stimulus that was for electrodes with the common
square 1,2 sm2.
In conclusion open the mechanism of development of space summation.
Theme 3
Single contraction and tetanus of skeletal muscles
To establish stimulating electrodes over the nervus ulnaris more medial to
processus ulnaris. To inflict the stimulus with different frequency. Pay attention on
the external manifestation of single contraction and tetanus of muscles, which are
innervated by nervus ulnaris.
Represent your results (single contraction and tetanuses) in your exercise book.
In conclusion define whether development the single contraction and tetanus of
skeletal muscles.
Electromyography of volitional conduction of muscles
To establish leading electrodes over the musculus biceps brachii (one
electrodes is situated on belly, other – on tendon). Inflict the upper threshold
stimulus. To bend slowly arm to maximal tension of musculus biceps brachii.
To calculate the frequency of active potential, which receiving on the
electromyograph‘s screen. The results represent in your exercise book.
In conclusion define the type of myogram, which was received.
Theme 4
Biceps-reflex
Make a stroke by neurologic hammer on the tendon of biceps above radial
bend. The hand of observed person must be semibent and maximally relaxed. With
this aim his forearm you must lie on forearm of observer. Call rellexon two hands.
Compare reactions. Represent schematically arc of the reflex in conclusion.
Triceps-reflex
Make a stroke by neurologic hammer on the tendon of m. triceps brachii above
radial process. The hand of observed person must be relaxed, bend in radial
articulation and abducted by observer on the back and outside. Call reflex on two
hands. Compare reactions. Represent schematically arc of the reflex in conclusion.
Patellar reflex
Make a stroke by neurologic hammer on the tendon of quadriceps of hip under
the patella. Observed person is sitting with compound legs. Muscle must be
relaxed. Call reflex on two legs, with and without test of Yendrasyk. Compare
reactions. Represent schematically arc of the reflex in conclusion.
Ahill reflex.
Offer observed person to stand on chair with freely hanging feet. Make a stroke
by nurologic hammer on Ahill's tendon to legs, with and without test of
Yendrasyk. Compare reactions. Represent schematically arc of the reflex in
conclusion.
Indicate about what received results testify, from what results and why are they
arising these reflexes.
Students’ Independent Study Program
Objectives for Students’ Independent Studies
You should prepare for the practical class using the existing textbooks and lectures.
Special attention should be paid to the following:
Theme 1
1. Common characteristic of synaptic and junction transmission (Impulses are
transmitted from one nerve cell to another at synapses. These are the junctions
where the axon or some other portion of one cell (the presynaptic cell) terminates
on the soma, the dendrites, or some other portion of another neuron (the
postsynaptic cell). It is worth noting that dendrites as well as axons can be
presynaptic or postsynaptic. Transmission at most of the junctions is chemical; the
impulse in the presynaptic axon liberates a chemical mediator. The chemical
mediator binds to receptors on the surface of the postsynaptic cell, and this triggers
intracellular events that alter the permeability of the membrane of the postsynaptic
neuron. At some of the junctions, however, transmission is electrical, and at a few
conjoint synapses it is both electrical and chemical. In any case, impulses in the
presynaptic fibers usually contribute to the initiation of conducted responses in the
postsynaptic cell, but transmission is not a simple jumping of one action potential
from the presynaptic to the postsynaptic neuron. It is a complex process that
permits the grading and modulation of neural activity necessary for normal
function.
In the case of electrical synapses, the membranes of the presynaptic and
postsynaptic neurons come close together, forming a gap junction. Like the
intercellular junctions in other tissues, these junctions form low-resistance bridges
through which ions pass with relative ease. Electrical and conjoint synapses occur
in mammals, and there is electrical coupling, for example, between some of the
neurons in the lateral vestibular nucleus. However, most synaptic transmission is
chemical.
Transmission from nerve to muscle resembles chemical synaptic transmission.
The myoneural junction, the specialized area where a motor nerve terminates on a
skeletal muscle fiber, is the site of a stereotyped transmission process. The contacts
between autonomic neurons and smooth and cardiac muscle are less specialized,
and transmission is a more diffuse process.)
a) Classification of synapses (For localization – central (neuro-neuronal) and
peripheral (neuro-muscles, neuro-secretion; central synapses may be axo-somatic,
axo-dendrites, axo-axonal, dendro-dendrites; for functional meaning – excitatory
and inhibitory; for the method of transmission – electrical and chemical.
There is considerable variation in the anatomic structure of synapses in various
parts of the mammalian nervous system. The ends of the presynaptic fibers are
generally enlarged to form terminal buttons (synaptic knobs). Endings are
commonly located on dendritic spines, which are small knobs projecting from
dendrites. In some instances, the terminal branches of the axon of the presynaptic
neuron form a basket or net around the soma of the postsynaptic cell (“basket
cells” of the cerebellum and autonomic ganglia). In other locations, they intertwine
with the dendrites of the postsynaptic cell (climbing fibers of the cerebellum) or
end on the dendrites directly (apical dendrites of cortical pyramids) or on the axons
(axo-axonal endings). In the spinal cord, the presynaptic endings are closely
applied to the soma and the proximal portions of the dendrites of the postsynaptic
neuron. The number of synaptic knobs varies from one per postsynaptic cell (in the
midbrain) to a very large number. The number of synaptic knobs applied to a
single spinal motor neuron has been calculated to be about 10,000, with 2000 on
the cell body and 8000 on the dendrites. Indeed, there are so many knobs that the
neuron appears to be encrusted with them. The portion of the soma membrane
covered by any single synaptic knob is small, but the synaptic knobs are so
numerous that, in aggregate, the area covered by them all is often 40 % of the total
membrane area. In the cerebral cortex, it has been calculated that 98 % of the
synapses are on dendrites and only 2 % are on cell bodies.)
b) Structure of synapses (All synapses consist of: presynaptic membrane,
postsynaptic membrane, synaptic cleft, subsynaptic membrane.)
c) Excitatory postsynaptic porential (Single stimuli applied to the sensory
nerves in the experimental situation described above characteristically do not lead
to the formation of a propagated action potential in the postsynaptic neuron.
Instead, the stimulation produces either a transient, partial depolarization or a
transient hyperpolarization.
The depolarizing response produced by a single stimulus to the proper input
begins about 0,5 ms after the afferent impulse enters the spinal cord. It reaches its
peak 1-1,5 ms later and then declines exponentially, with a time constant (time
required for the response to decay to 1/e, or 1/2,718 of its maximum) of about 4
ms. During this potential, the excitability of the neuron to other stimuli is
increased, and consequently the potential is called an excitatory postsynaptic
potential (EPSP).
The EPSP is due to depolarization of the postsynaptic cell membrane
immediately under the active synaptic knob. The area of inward current flow thus
created is so small that it will not drain off enough positive charges to depolarize
the whole membrane. Instead, an EPSP is inscribed. The EPSP due to activity in
one synaptic knob is small, but the depolarizations produced by each of the active
knobs summate.
Summation may be spatial or temporal. When activity is present in more than
one synaptic knob at the same time, spatial summation occurs and activity in one
synaptic knob is said to facilitate activity in another to approach the firing level.
Temporal summation occurs if repeated afferent stimuli cause new EPSPs before
previous EPSPs have decayed. The EPSP is therefore not an all or none response
but is proportionate in size to the strength of the afferent stimulus. If the EPSP is
large enough to reach the firing level of the cell, a full-fledged action potential is
produced.)
d) Synaptic delay (When an impulse reaches the presynaptic terminals, there is
an interval of at least 0,5 ms, the synaptic delay, before a response is obtained in
the postsynaptic neuron. The delay following maximal stimulation of the
presynaptic neuron corresponds to the latency of the EPSP and is due to the time it
takes for the synaptic mediator to be released and to act on the membrane of the
postsynaptic cell. Because of it, conduction along a chain of neurons is slower if
there are many synapses in the chain than if there are only a few. This fact is
important in comparing, for example, transmission in the lemniscal sensory
pathways to the cerebral cortex and transmission in the reticular activating system.
Since the minimum time for transmission across one synapse is 0,5 ms, it is also
possible to determine whether a given reflex pathway is monosynaptic or
polysynaptic (contains more than one synapse) by measuring the delay in
transmission from the dorsal to the ventral root across the spinal cord.)
2. Common characteristic of electrical synapses (Electrical synapses is the
junctions in which the transmission of information do through the direct passage of
bioelectrical signal from cell to cell. This synapses has small synaptic split (to 5
nm), low specific resistance between the presynaptic and postsynaptic membranes.
There are the transverse canals in both membranes with the diameter of 1 nm..)
a) Excitatory transmitter (Excitatory impulses go to the synapse and increase
permeability of postsynaptic cell membrane to Na+.)
b) Inhibitory transmitter (Inhibitory impulses go to the synapse and increase
permeability of postsynaptic cell membrane to Cl-, not to Na+.)
3. Common characteristic of chemical synapses (Chemical synapses is the
junctions in which the transmission of information do through the direct passage
with chemical substances from cell to cell. These substances named mediators.)
a) Classification of chemical synapses (These synapses named for the type of
mediator – cholinergic (mediator – acetylcholine), adrenergic (mediator –
epinephrine, norepinephrine), serotonin (mediator – serotonin), dopaminenergic
(mediator – dopamin), GABA-ergic (mediator – gamma-aminobutyric acid).
b) Chemical transmission of synaptic activity (Active membrane potential go
along the nerve to presynaptic end – presynaptic membrane have depolarilazed –
the Ca2+-cannals activated – Ca2+-go to the presynaptic end – Ca2+-activated
transport of vesiccles with the mediator along the neurofilaments to presynaptic
membrane – the mediator pick out from presynaptic ends to the synaptic split –
molecules of mediator diffuse through the synaptic split to postsynaptic membrane
– molecules of mediator interact with the receptors on the postsynaptic membrane
– this interaction lead to the conformation of receptors and activation of
corresponding substances.)
Key words and phrases: synapses, the presynaptic cell, the postsynaptic cell,
chemical mediator, electrical synapses, chemical synapses, conjoint synapses,
myoneural junction, neuro-neuronal, neuro-muscles, neuro-secretion, axo-somatic,
axo-dendrites, axo-axonal, dendro-dendrites, excitatory and inhibitory synapses,
terminal buttons, synaptic knobs, dendritic spines, time constant, excitatory
postsynaptic potential (EPSP), spatial or temporal summation, facilitate activity,
synaptic delay, specific resistance
Theme 2
1. Functionally-structures peculiarities of nervous system
a) Neuron as a structurally-functional unit (The bases of nervous system are
neurons. They have body or soma and axons and dendrites. Physiological role of
axons is transmition of neurons impulses from soma to other neurons or organs, the
physiological role of dendrites is supplying of information to the neurons body.
The axon hillock has a maximal excitability in neurons. Neuron may be in the rest
condition (absent change of rest membrane potential) and active condition (may
generate active potential), and inhibition condition (stop the impulses activity of
the neuron).
Classification of nervous cells according to functioning meaning:
1) Sensory or afferent (to perceive irritation and transmit excitement in central
nervous system); 2) Interneurons (to help spreading of excitement in neurons nets
or act inhibition); 3) moving (motor or efferent) – to transmit the excitement to
working organs.
Mediators help to connect the neurons. There are excitable (glutamine acid,
acetylcholine) and inhibitory (gamma-ammino-butiric acid – GABA, glycin)
mediators.
b) Axon transport (There are 2 kinds of axon transport: fast and slow. Fast
transport provides transmition of mitochondria, vesicles with mediators. It speed is
250-400 mm per day. These transport stop when destroyed microtubules and
neurofilaments and if absent in axon ATP and Ca2+. Fast transport may transmit
substances from the neurons' body (anterogrades transport) and to body
(retrogrades transport). By help of fast anterogrades transport transmit substances
and structures which very important for synaptic action; by help of fast retrogrades
transport moving trophogens, which need for nutritient of neurons, and products of
axons' metabolism. Slow axon transport is a transmition of all mass of cytoplasm
in distal direction. It stops in the case of separation soma from axon. It need to
axons' growth and provide trophic in postsynaptic cells.)
c) Role of glia cells (The neurons of the central nervous system are supported
by several varieties of non-excitable cells that are called the neuroglia. There are
four types of neuroglial cells: astroglia, oligodendroglia, microglia, epindima. They
have insulating function, produce myelin, have secretor role, absorbed from
intercells fluid K+.)
2. Peculiarities of excitement transmition in neural chain
a) Divergence and irradiation (Neurons may to connected by synapses with
different nervous cells. This property has the notion divergence. If it will be an
active transmition of excitement it is called irradiation.)
b) Convergence (On the each neuron of central nervous system may come
together different afferent impulses. That is why in one neuron coming at the same
time different excitement. Later it analyzing and formed in one axon excitement
that goes to other chain of nervous net.)
c) Reverberation (In central nervous system are present the nervous chain of
own excitement. They arise at the answer of stimulus and excitements in these
chains are circulated to the time, when other external stimulus inhibits it or it tired.
Reverberation is a base of short-time memory.)
d) Time summation (It is a rise of excitement in the case of action under
threshold stimulus. If the frequency of stimulus sufficiently big, excitive
postsynaptic potential amount to firing level of depolarization and active potential
arise.)
e) Space summation (It is a rise of excitement because of simultaneous action
of several under-threshold stimuli. In these case excitive postsynaptic potential
amount to the firing level of depolarization or may be more and active potential
arise.)
f) Occlusion (On account of divergence one neuron may pass excitive signals
on the other neurons. Another neuron may excite several neurons. But if from both
neurons which are divergented excitement will be simultaneously the total quantity
of excited neurons will be decrease.)
3. Inhibition in the nervous system (Inhibition is an active reaction which add to
the oppression or prevention of excitement.)
a) Postsynaptic inhibition (Excitement, which are coming to the inhibitory
neuron – Renshow cell of spinal cord, Purkinje cell of cerebellum, astrocites of
cortex of big hemisphere – help to produce an inhibitory mediator of this cell
(GABA, glycin). According to this act, increase activity of K+ channels of
postsynaptic cells, which lead to the hyperpolarization. As result – decrease of
activity of Na+ channels and possibility of development of depolarization in the
excitive cell.)
b) Presynaptic inhibition (It may be between axons of excitive and inhibitory
neurons. Inhibitory mediator cause hyperpolarization of axon of excitable neuron,
prevent arriving of active potential to presynaptic end and as result decrease
production of mediator for the development of excitement in postsynaptic cell.)
c) Opposite inhibition (Collaterals of axons of excitive nervous cells are form
synaptic connection with inhibitory neurons. These inhibitory neurons have
synaptic connection with these excitive neurons. In the case of excitement of
excitive neuron activated inhibitory neuron, which produce GABA or glycin in
synaptic cleft. As a result, occur hyperpolarization of membrane of excitive neuron
and it activity inhibited. Opposite inhibition may be presynaptic or postsynaptic.)
d) Lateral inhibition (If in a neurons' chain, which secure opposite inhibition
collaterals of axons of inhibition neurons form synaptic connection with
neighboring excitive cells in these cells develop lateral inhibition.)
4. Common characteristic of reflexes (Reflex is a change of functional activity of
tissues, organs or whole organism as an answer on stimulus by help of central
neural system.)
a) Structure of reflector arc (Reflector arc is a structure base of reflex. It consist
of 1. receptors, which are perceive different influences which are act on organism;
2. afferent neurons, which connect receptors with central nervous system; 3.
central part of central nervous system, which realize analyses and synthesis of
afferent information; 4. efferent chain secure going out of excitement from central
nervous system; 5. effector is executive organ; 6. opposite connection.)
b) Classification of reflexes (1. According to the biological meaning: food,
defensive, oriental, homeostatic, sex. 2. According to the position of receptors:
exteroreceptors (skin, vision, hearing, smell), interoreceptors (visceroreceptors –
from inner organs) and proprioreceptors (from muscular, tendons, joints). 3.
According to the level of close of reflector arc: spinal, bulbar, mesencephalon,
diencephalon, cortex. 4. According to the character of answer: moving, secretory,
vessel-moving. 5. According to the duration of answer: fase, tonic. 6. According to
the quantity of synapses in central chain: monosynaptic, polisynaptic. 7. According
to the kind of efferent part of reflectory arc: somatic, autonomic. 8. According to
the position of effector: moving, vessels, heart, secretory, etc. 9. According to the
adaptative meaning: physiological, pathological.)
Key words and phrases: sensory or afferent neuron, interneuron, moving
(motor or efferent) neuron, gamma-ammino-butiric acid – GABA, glycin, axon
transport, fast and slow transport, anterogrades transport, retrogrades transport,
neuroglial cells, astroglia, oligodendroglia, microglia, epindima, divergence,
irradiation, convergence, reverberation, time summation, space summation,
occlusion, inhibition; postsynaptic, presynaptic, opposite, lateral inhibition
Theme 3
1. Characteristic of skeletal muscles
a) Resting and active potentials of muscle fiber (The electrical events in
skeletal muscle and the ionic fluxes underlying them are similar to those in nerve,
although there are quantitative differences in timing and magnitude. The resting
membrane potential of skeletal muscle is about -90 mV. The action potential lasts
2-4 ms and is conducted along the muscle fiber at about 5 m/s. The absolute
refractory period is 1-3 ms long and the after-polarizations, with their related
changes in threshold to electrical stimulation, are relatively prolonged. The
chronaxie of skeletal muscle is generally somewhat longer than that of nerve.
Although the electrical properties of the individual fibers in a muscle do not
differ sufficiently to produce anything resembling a compound action potential,
there are slight differences in the thresholds of the various fibers. Furthermore, in
any stimulation experiment, some fibers are farther from the stimulating electrodes
than others. Therefore, the size of the action potential recorded from a whole
muscle preparation is proportionate to the intensity of the stimulating current
between threshold and maximal current intensities. The distribution of ions across
the muscle fiber membrane is similar to that across the nerve cell membrane. As in
nerve, depolarization is a manifestation of Na+ influx, and repolarization is a
manifestation of K+ efflux.)
b) Electromyography (Activation of motor units can be studied by
electromyography, the process of recording the electrical activity of muscle on a
cathode-ray oscilloscope. This may be done in humans by using small metal disks
on the skin overlying the muscle as the pick-up electrodes or in un anesthetized
humans or animals by using hypodermic needle electrodes. The record obtained
with such electrodes is the electromyogram (EMG). With needle electrodes, it is
usually possible to pick up the activity of single muscle fibers.)
c) Connection between excitation and contraction (It is important to distinguish
between the electrical and mechanical events in muscle. Although oneresponse
does not normally occur without the other, their physiologic basis and
characteristics are different. Muscle fiber membrane depolarization normally starts
at the motor end-plate, the specialized structure under the motor nerve ending.
A single action potential causes a brief contraction followed by relaxation. This
response is called a muscle twitch; the action potential and the twitch are plotted
on the same time scale. The twitch starts about 2 ms after the start of
depolarization of the membrane, before repolanzation is complete. The duration of
the twitch varies with the type of muscle being tested. “Fast” muscle fibers,
primarily those concerned with fine, rapid, precise movement, have twitch
durations as short as 7.5 ms. “Slow” muscle fibers, principally those involved in
strong, gross, sustained movements, have twitch durations up to 100ms.)
d) Solitary contraction (The process by which the shortening of the contractile
elements in muscle is brought about is a sliding of the thin filaments over the thick
filaments. The width of the A bands is constant, whereas the Z lines move closer
together when the muscle contracts and farther apart when it is stretched. As the
muscle shortens, the thin filaments from the opposite ends of the sarcomere
approach each other; when the shortening is marked, these filaments apparently
overlap.
The sliding during muscle contraction is produced by breaking and re-forming
of the crosslinkages between actin and myosin. The heads of the myosin molecules
link to actin at an angle, produce movement of myosin on actin by swiveling, and
then disconnect and reconnect at the next linking site, repeating the process in
serial fashion. Each single cycle of attaching, swiveling, and detaching shortens the
muscle 1 %.
The immediate source of energy for muscle contraction is ATP. Hydrolysis of
the bonds between the phosphate residues of this compound is associated with the
release of a large amount of energy, and the bonds are therefore referred to as highenergy phosphate bonds. In muscle, the hydrolysis of ATP to adenosine
diphosphate (ADP) is catalyzed by the contractile protein myosin; this adenosine
triphosphatase (ATPase) activity is found in the heads of the myosin molecules,
where they are in contact with actin.
The process by which depolarization of the muscle fiber initiates contraction is
called excitation-contraction coupling. The action potential is transmitted to all
the fibrils in the fiber via the T system. It triggers the release of Ca 2+ from the
terminal cisterns, the lateral sacs of the sarcoplasmic reticulum next to the T
system. The Ca2+ initiates contraction. Ca2+ initiates contraction by binding to
troponin C. In resting muscle, troponin I is tightly bound to actin, and tropomyosin
covers the sites where myosin heads bind to actin. Thus, the troponin-tropomyosin
complex constitutes a “relaxing-protein” that inhibits the interaction between actin
and myosin. When the Ca2+ released by the action potential binds to troponin C,
the binding of troponin I to actin is presumably weakened, and this permits the
tropomyosin to move laterally. This movement uncovers binding sites for the
myosin heads, so that ATP is split and contraction occurs.
Shortly after releasing Ca2+, the sarcoplasmic reticulum begins to reaccumulate
Ca2+. The Ca2+ is actively pumped into longitudinal portions of the reticulum and
diffuses from there to the cisterns, where it is stored. Once the Ca 2+ concentration
outside the reticulum has been lowered sufficiently, chemical interaction between
myosin and actin ceases and the muscle relaxes. If the active transport of Ca 2+ is
inhibited, relaxation does not occur even though there are no more action
potentials; the resulting sustained contraction is called a contracture. It should be
noted that ATP provides the energy for the active transport of Ca2+ into the
sarcoplasmic reticulum. Thus, both contraction and relaxation of muscle require
ATP.
e) Types of Contraction (Muscular contraction involves shortening of the
contractile elements, but because muscles have elastic and viscous elements in
series with the contractile mechanism, it is possible for contraction to occur
without an appreciable decrease in the length of the whole muscle. Such a
contraction is called isometric (“same measure” or length). Contraction against a
constant load, with approximation of the ends of the muscle, is isotonic (“same
tension”)).
f) Summation of contraction and tetanus of muscles (The electrical response of
a muscle fiber to repeated stimulation is like that of nerve. The fiber is electrically
refractory only during the rising and part of the falling phase of the spike potential.
At this time, the contraction initiated by the first stimulus is just beginning.
However, because the contractile mechanism does not have a refractory period,
repeated stimulation before relaxation has occurred produces additional activation
of the contractile elements and a response that is added to the contraction already
present. This phenomenon is known as summation of contractions. The tension
developed during summation is considerably greater than that during the single
muscle twitch. With rapidly repeated stimulation, activation of the contractile
mechanism occurs repeatedly before any relaxation has occurred, and the
individual responses fuse into one continuous contraction. Such a response is
called a tetanus (tetanic contraction). It is a complete tetanus when there is no
relaxation between stimuli, and an incomplete tetanus when there are periods of
incomplete relaxation between the summated stimuli. During a complete tetanus,
the tension developed is about 4 times that developed by the individual twitch
contractions.
The stimulation frequency at which summation of contractions occurs is
determined by the twitch duration of the particular muscle being studied. For
example, if the twitch duration is 10 ms, frequencies less than 1/10 ms (100/s)
cause discrete responses interrupted by complete relaxation, and frequencies
greater than 100/s cause summation.)
2. Peculiarities of smooth muscles
a) Resting membrane (It may be from –50 mV to –60 mV. In this process take
place K+, Na+, Cl-. There are a large concentration of Na+, Cl- in the cells.)
b) Active potential (Prolongation of it may be from 20-50 ms to 1 second;
amplitude is less that in skeletal muscles. Active potential end by afterhyperpolarization. The main role in the beginning of it have Ca+.)
c) Elasticity, plasticity and tensility (Another special characteristic of smooth
muscle is the variability of the tension it exerts at any given length. If a piece of
visceral smooth muscle is stretched, it first exerts increased tension. However, if
the muscle is held at the greater length after stretching, the tension gradually
decreases. Sometimes the tension falls to or below the level exerted before the
muscle was stretched. It is consequently impossible to correlate length and
developed tension accurately, and no resting length can be assigned. In some ways,
therefore, smooth muscle behaves more like a viscous mass than a rigidly
structured tissue, and it is this property that is referred to as the plasticity of
smooth muscle.
The consequences of plasticity can be demonstrated in the intact animal. For
example, the tension exerted by the smooth muscle walls of the bladder can be
measured at varying degrees of distention. After each addition of fluid, the tension
was measured for a period of time. Immediately after each increment of fluid, the
tension was higher; but after a short period of time, it decreased.)
3. Characteristic of cardiac muscle
a) Resting membrane and action potential of cardiac muscle cells (The resting
membrane potential of individual mammalian cardiac muscle cells is about -80 mV
(interior negative to exterior). Stimulation produces a propagated action potential
that is responsible for initiating contraction. Depolarization proceeds rapidly and
an overshoot is present, as in skeletal muscle and nerve, but this is followed by a
plateau before the membrane potential returns to the baseline. In mammalian
hearts, depolarization lasts about 2 ms, but the plateau phase and repolarization last
200 ms or more. Repolarization is therefore not complete until the contraction is
half over.
As in other excitable tissues, changes in the external K+ concentration affect the
resting membrane potential of cardiac muscle, whereas changes in the external Na +
concentration affect the magnitude of the action potential. The initial rapid
depolarization and the overshoot are due to a rapid increase in Na+ permeability
similar to that occurring in nerve and skeletal muscle, whereas the second plateau
phase is due to a slower starting, less intense, and more prolonged increase in Ca 2+
permeability. The third phase is the manifestation of a delayed increase in K+
permeability. This increase produces the K+ efflux that completes the
repolarization process. The Na+ channel in cardiac muscle is often called the fast
channel. It probably has 2 gates, an outer gate that opens at the start of
depolarization, at a membrane potential of -60 to -70 mV, and a second inner gate
that then closes and precludes further influx until the action potential is over (Na +
channel inactivation). The Ca2+ channel is called the slow channel. It is activated at
a membrane potential of -30 to -40 mV and inactivates much more slowly than the
fast channel.)
b) Mechanic properties (The contractile response of cardiac muscle begins just
after the start of depotanzation and lasts about 1,5 times as long as the action
potential. The role of Ca2+ in excitation-contraction coupling is similar to its role in
skeletal muscle, except that Ca2+ entering from the ECF as well as Ca2+ from the
sarcoplasmic reticulum contributes to contraction. Responses of the muscle are all
or none in character, ie, the muscle fibers contract fully if they respond at all. Since
cardiac muscle is absolutely refractory during most of the action potential, the
contractile response is more than half over by the time a second response can be
initiated. Therefore, tetanus of the type seen in skeletal muscle cannot occur. Of
course, tetanizalion of cardiac muscle for any length of time would have lethal
consequences, and in this sense the fact that cardiac muscle cannot be tetanized is a
safety feature. Ventricular muscle is said to be in the “vulnerable period” just at the
end of the action potential, because stimulation at this time will sometimes initiate
ventricular fibrillation.)
Key words and phrases: elasticity, tensility, tetanus, summation of contraction,
electromyography, excitation, contraction, solitary contraction, spontaneous
activity, myosin, actin, tropomyosin, troponin, troponin I, troponin T, troponin C,
excitation-contraction coupling, the terminal cisterns, contracture, isometric,
isotonic, tetanic contraction, complete tetanus, incomplete tetanus, plateau,
plasticity
Theme 4
1. Functionally-structural characteristic of spinal cord.
a) Functions, macroscopic structure (The functions of spinal cord are
transmitting the impulses and reflectory function. Spinal cord has segmental
structure. It consist of 31-33 segments: 8 cervical, 12 thoracic, 5 lumbal, 5 sacral
and from 1 to 3 coccigea. Every segment has two pairs of ventral and dorsal roots:
right and left. In outer layer present the white substance, where pass conduction
tracts, and in inner layer present grey matter, where present nucleus. Segmental
principle of work connects with segmental structure of spinal cord. Spinal reflexes
are reflexes, which reflex arc are locked on level of segment of spinal cord. They
are tendinous and dermal reflexes. For example, knee reflex is locked on L III-LIV
level. Reflexes between segments whose reflex arcs are locked on many segments.
For example, vessels` reflex – on ThI– LII level.)
b) Property of neurons elements (Body of sensory cell are present outside the
spinal cord. Some of them are present in spinal ganglion (they innervate the
sceletal muscles). Other are present in extra- and intramural ganglions of
autonomic nervous system and provide sensitivity of inner organs. The nervous
fibers of sensory cells may be myelinated (v=12-120 m/s) and nonmyelinated (v=2
m/s). They go to spinal cord from pain, chemo- and some mechanoreceptors. 3 %
of all neurons are moving, 97 % are interneurons. There are α- and γ-motoneurons.
α-motoneurons transmit signals from spinal cord to celetal muscles. γ-motoneurons
(30 %) innervate intrausal muscles fibers. Excitement of the fibers lead to the
contraction or relaxation of extrafusal muscles fibers.)
c) Interposed of afferent and efferent fibers on peripheral part (Bell-Magandy`s
law: in the spinal cord the dorsal are sensory, the ventral roots are motors. Quantity
of sensory fibers in posterior roots in 20 time more than moving in arterior.)
2. Reflectory activity of spinal cord.
a) Elicity and reflectory arc of miotatic reflexes: elbow, knee, achill (Spinal
somatic reflexes are totally of simple pose and motor acts, which can be realized
without participation of higher parts of central nervous system. Stretch reflexes are
monosynaptic. Extention, flexor reflexes – polysynaptic, spinal locomotor reflexes
are transference. They provide by the help of coordinated movements of limbs.
Programated on spinal level It is autonomic movement. Characteristics of elbow,
knee, Achilles, plantar and abdominal reflexes. Elbow, knee, Achilles reflexes are
monosynaptic, myotatic reflexes. They have segmental character. They are locked
on level: elbow – CV– CVI , knee – LII– LIV, Achilles SI– SII.
Plantar and abdominal are dermal monosynaptic reflexe. Are locked on level:
plantar – Th12. Superior abdominal Th8 - Th9, medius abdominal Th9–Th10, inferior
abdominal – Th11–Th12.
Reflex arcs of tendinous relflex are: knee reflex – intrafusal fibers of m.
quadriceps femoris – n. femoralis – LII - LIV – n. femoralis – extrafusal fibers of m.
quadriceps femoris.
Achilles reflex – intrafusal fibers of m. gastrocnemius – n. ischiadicus – SI-SII –
n. tibialis – extrafusal fibers of m. gastrocnemius.
Elbow flexor reflex – intrafusal fibers of m. biceps brachii – n.
musculocutaneus – CV-CVI – n. musculocutaneus – extrafusal fibers of m. biceps
brachii.
Elbow extension reflex - intrafusal fibers of m. triceps brachii – n. radialis –
CVII-CVIII – n. radialis – extrafusal fibers of m. triceps brachii.
b) Mechanism of development of miotatic reflexes (Muscle spindle consist of
nucleus bag (central part) and intrafusal muscles fibers. Spindles connect to the
exstrafusal fibers. The quantity of spindles increase in the case of direct muscles'
moving. In the nucleus bag present nervous ending (like-spirale), this has receptor
function. From begining of afferent fiber, which transmit excitement fast. Nervous
ending may excited in the case of cotraction of muscles fibers. γ-motoneurons have
the influence on contraction of it too. γ-motoneurons help to contract the intrafusal
fibers. These is a course of stretch of nervous ending in nucleus bag. The quantity
of impulses to spinal cord are increase. Sensor neurons end near α-motoneurons,
excite them and as result extrafusal fibers are contract. These is a base of myotatic
reflexes.)
c) Meaning of invistigation of spinal reflexes (It very important for neurologic
department to determing the place of destruction of spinal cord.)
d) Bent and cross-unbend reflexes (Cross-unbend reflexes are in the base of
locomotor acts and characterised by inhibition of motoneurons of extensor muscles
in the same time of excitement of motoneurons of flexor muscles. At this time on
the leg and arm of opposite side present opposite reaction. In the stretch reflexes
more high tone are in muscles extensor. They help support the static and pose of
body.)
3. Functional meaning of spinal cord' tracts (There are 2 kinds of tracts: ascendens
and descendens. Ascendens tract are sensory, descendens are motor.)
a) Ascendens (Ascending tracts are sensory. They conduct information from
external environment to the higher situated centers of encephalon. They are
conductors of information from enternal surroundings to the higher part of central
nervous system. Goll`s tract (fasciculus gracilis), Burdach`s tract (fasciculus
cuneatus) are situated in postirior columnus. They are conducters of tactive and
proprioceptive (for example, muscles-elbow) sensorities from down and upper part
of the body. Tractus spinothalamicus is situated in lateral columnus. They carry
pain, temperature – tractus spinothalamicus dorsalis and spinotectalis – and tactil –
tractus spinothalamicus ventralis – sensetivities from body to thalamus.)
b) Descendens (Descending tracts are motors. Corticospinal tract (tractus
corticospinalis lateralis) is basic motor tract. It is passing in side columns. It is a
conductor of impulses to the skeletal muscles, is regulating free movements.
Monacow`s tract (rubrospinalis) – in side columns, regulate tone of skeletal
muscles.
Tractus vestibulospinal dorsalis is present in side columns regilate equilibrium
and supporting of pose. Olivospinal tract – in side columns – may be takes part in
thalamospinal reflexes. Reticulospinal tract – in front columns – is regulating the
tone of skeletal muscles, vegetative spinal centers. Vestibulospinal tract – in front
columns – regulates equilibrium and supporting of pose.)
Key words and phrases: spinal cord, segments, reflex function, guide function,
efferent neurons, afferent neurons, tendinous reflex.
Students must know:
Theme 1
1. Ultrastructure of electrical and chemical synapses
2. Excitatory and inhibitory mediators
Theme 2
1. Axon transport of substances through the neuron
2. Peculiarities of excitement transmition in neural chain
3. Inhibition in nervous system
4. Excitatory and inhibitory mediators
Theme 3
1. Ultrastructure of muscles
2. Mechanism of muscle‘s energy security
Theme 4
1. The main characteristics of spinal cord.
2. All arcs of reflexes.
Students should be able to:
Theme 1
1. To analyze the modern registers about the molecular mechanisms of synaptic
transmission in the skeletal and smooth muscles
Theme 2
1. To analyze the mechanism of development of excitement transmition in neural
chain
2. To analyze the mechanism of development of inhibition in neural chain
Theme 3
1. To analyze the peculiarities of physiological properties and physiological
processes of skeletal, smooth and cardiac muscles
Theme 3
1.Call all the reflexes.
Tests and Assignments for Self-assessment
Multiple Choice.
Choose the correct answer/statement:
Theme 1
1. What are the more sensitive to epinephrine kind of receptors?
a) 1-adrenergic; b) 2-adrenergic; c) 1-adrenergic; d) 2-adrenergic; e) Mcholinergic
2. What are sensitive to epinephrine and norepinephrine kind of receptors?
a) 1-adrenergic; b) 2-adrenergic; c) 1-adrenergic; d) 2-adrenergic; e) Mcholinergic
3. What are sensitive to acetylcholine kind of receptors?
a) -adrenergic; b) -adrenergic; c) nicotinic; d) muscarinic; e) cholinenergic
4. Acetylcholine breaking on … by…:
a) on acetyl-CoA and choline, by acetylcholinesterase; b) on acetyl-CoA and
choline, by monoamine oxidase; c) on acetyl-CoA and choline, by catechol-O-
methyltransferase; d) on dopamine, by dopa decarboxylase; e) on Dopa, by
tyrosine hydroxylase
Real-life situations to be solved:
1. Neuro-muscles preparation of frog was stimulated with the 250 impulses per
second. What was reduce of muscle‘s frequency?
Answers for the Self-Control
1. d; 2. c; 3. e; 4. a
1 real-life situation – Reduce of muscle‘s frequency was only 100 impulses per
second, because the lability of synapse only 100 impulses per second.
Theme 2
1. What are the kind of inhibition in the case of increase of potassium ions in outer
side of memsrane?
a) Postsynaptic; b) Presynaptic; c) Lateral; d) Opposite
2. You are studying. What are the ways of excitement transmition in neural chain
in Your brain?
a) divergence; b) irradiation; c) convergence; d) reverberation; e) time
summation
3. You are play football. What are the ways of excitement transmition in neural
chain in Your brain?
a) divergence; b) irradiation; c) convergence; d) reverberation; e) time
summation; f) space summation
4. What is the inhibitory mediator of interneurons of spinal cord?
a) glycin; b) acetylcholine; c) epinephrine; d) glutamine acid; e) serotonin
5. What is the main excitive mediator of neurons?
a) glycin; b) acetylcholine; c) epinephrine; d) glutamine acid; e) serotonin
Real-life situations to be solved:
1. At the morning You stand up by help of alarm-clock after 5 or more signals of it.
Why You don't stand up after first signal?
Answers for the Self-Control
1. a; 2. all answer are though; 3. all answer are though; 4. a; 5. d
1 real-life situation – We stand up after 5 or more signal because in these case will
be time summation of under threshold stimulus and after 1 signal we don't may
awakening.
Theme 3
1. What are the peculiarities of the contraction of smooth muscles?
a) Absent of T-system; b) Absent of Ca2+; c) Small quantity of Ca2+; d) Good
development of T-system; e) Large concentration of Ca2+
2. What the main ions, which take place in the development of active potential?
a) Ca2+; b) Na+; c) K+; d) Cl-; e) H+
Real-life situations to be solved:
1. What is the changing of myogram when increase the active potential frequency
of individual fibers?
2. What is the changing of myogram when increase the quantity of simultaneously
stimulated fibers of muscles?
Answers for the Self-Control
1. a; 2. a
1 real-life situation – 1. On the myogram increased the frequency and amplitude of
summer‘s active potential, which are leading from muscles. 2. On the myogram
increased the amplitude of summer‘s active potential, which are leading from
muscles
Theme 4
1. Reflex arc of knee reflex is locked on level:
a) LIII – LIV; b) SI – SII; c) LI – LII; d) LIV – SI; e) LIII
2. Reflex arc of albow reflex is locked on level:
a) CIV – CV; b) CV – CIV; c) CVII – CVIII; d) ThI – ThII; e) ThV
3. Which tracts of spinal cord are motor:
a) Goll`s tract; b) Monakow`s tract; c) Flexig`s tract; d) Gower`s tract; e)
Pyramidal tract.
Real-life situations to be solved:
1. Traumatic rupture of person' spinal cord on Th I – ThII arised after automobile
catastrophe. Such symptoms arise after this: free movements disappeared, tactive,
temperature, pain sensivities are lost.
a) How can you call this status?
b) Explain arising the symptoms?
III. Answers for the Self-Control
1. c; 2. b, c; 3. e;
1 real-life situation – a) spinal shock; b) disappearing of free movements can be
explained violation of pyramidal tracts; disappearing of sensivity can be explained
by violation of spinothalamic tract , Goll`s and Burdach`s tracts.
References:
1. Review of Medical Physiology // W.F.Ganong. – Twentieth edition, 2001. – P.
62-84, 90-91, 95-96. 110-113. 123-128. 130
2. Textbook of Medical Physiology // A.C.Guyton, J.E.Hall. – Tenth edition, 2002.
– P. 67-78, 80-94, 96-99.512-525. 622-632.
Methodical Instructions to Lesson 3 for Students
Themes:
1. PHYSIOLOGY OF HIND-BRAIN, MESENCEPHALON,
DIENCEPHALON.
2. PHYSIOLOGY OF ENCEPHALON AND CEREBELLUM
3. FUNCTIONAL ACTIVITY OF CORTEX OF ENCEPHALON
AND
Aim: To know the peculiarities of regulation of bulbar mesencephalon and
diencephalon and to show the specialization each of them which ensure the
perfection of central regulation. To realize the peculiarities of regulation
subcortical nuclei and cerebellum that reviling the specialization, which provides
the perfection of central regulation; to give some reasoning of somatical, sensorial
and psychological manifestation of functional asymmetry of the brain of excitable
tissues. To define physiological basis of electroencephalography and its
possibilities in physiologic anatomy of the cerebral cortex..
Professional Motivation: The knowledge of physiology of metencephalon,
mesencephalon and diencephalons is necessary for prospective physicians for
diagnosis of different diseases. The knowledge of the physiology of encephalon
and cerebellum is necessary for prospective physicians to value the condition of
whole organism. The knowledge of cortex of encephalon and methods of its
registration is necessary for future physicians to value the functional conditions of
encephalon activity.
Basic Level:
1.Structure of metencephalon, mesencephalon and diencephalons. Structure of big
hemispheres Structure of cerebellum. Structure of cortex of encephalon (Anatomy
Course).
2.Nuclear composition of metencephalon, mesencephalon. Microstructure of
encephalon and cerebellum (Histology Course).
Students` practical Activities:
Theme 1
Superciliar reflex
Make a light stroke by neurologic hammer on margin of superciliar arc. Call
reflex on both sides. Compare reactions. Represent schematically arc of the reflex
in conclusion.
Lid reflex
Touch by small piece of cotton wool to the cornea. Compare reactions.
Represent schematically arc of the reflex in conclusion.
Mandibular reflex
Make the light stroke on chin (the mouth must be open). Pay attention to the
reaction. Represent schematically arc of reflex in conclusion.
Indicate about what received results testify.
Theme 2
Displays of functional encephalic asymetry
a) Somatic. Take hand dynamometer, abduct hand from the trunk at right angles.
Second hand put down along the trunk. Press with maximum strength fingers and
fix the pointer of dynamometer. Do so 5 times with intervals on some minutes.
Maximum deflection of the pointer of dynamometer shows maximum strength of
the hand’s. Make determination for both hands.
b) Psychical. Look attentively on proposed table. Determinate where is smile, and
where is grief.
The key to the test: left – hemispherial person on the first picture shows smile,
on the second – grief. Right – hemispherial – the other way round.
Indicate about what received results testify in conclusion.
Cerebellar tests
a) Finger – nasal test. Observed person must touch the end of the nose by index
finger. The hand must be straight and abduct to the back. Pay attention to the
availability of trembling. Fulfil test with opened and closed eyes.
b) Romberg’s test. Offer observed person to stand with put down hands, combined
foots and closed eyes. Pay attention is there shaking. If there is no shaking, offer to
pick hands up, appraise stability of observed person in present pose.
Indicate what functions of cerebellum this test shows.
Theme 3
Electroencelography
Fix electrodes in frontal, temporal and occipital states. Bioelectric activity of
encephalon is registrated when the person is relaxed with eyes closed and later
with eyes opened. Define the altitude and frequency of the electroencephalogram.
Show it as a scheme in the report.
In the conclusion answer what electroencephalogram reflects and what rhythms
were registered.
Students’ Independent Study Program
Objectives for Students’ Independent Studies
You should prepare for the practical class using the existing textbooks and lectures.
Special attention should be paid to the following:
Theme 1
1. Metencephalon (We mean that metencephalon or hind-brain is combain medulla
oblongata and pons.)
a) Neuronal composition, nuclei (Medulla oblongata is a continuation of spinal
cord. In medulla oblongata are present efferent neurons, interneurons, neurons of
asdendens and descendens tracts, ending of afferents neurons. Functions of
metencephalon are reflectory, conductive. The grey matter of hind-brain is present
in the look of congestion (nucleus). Classification of nucleus of medulla oblongata
according to functional properties: moving (n. nervus hypoglossus, n. nervus
accessorius), combain (n. nervus vagus, n. nervus glossopharyngeus), substantia
formatio reticularis. Classification of nucleus of pons: moving (n. nervus
abducens), sensetive (n. nervus vestibulocochlearis), combain (n. nervus facialis, n.
nervus trigeminus), substantia formatio reticularis.)
b) Reflexes (1. Chain reflexes are the compound reflector acts, in which one
reflexs is a direct cause of rise of future reflexes. In these reactions, take place
moving nucleus of medulla oblongata. These reflexes provide chewing and
swallowing of food.
2. Reflexes, which are direct on supporting of muscle tone are neck and
vestibular. Neck reflexes send up in the case of excitement of proprioreceptors of
neck muscles. In these cases change the tone of extensor muscles. If the head
throw at backward the tone of muscles extensor of upper extremities increase and
tone of muscles extensor of lower extremities decrease. If the head put down the
tone of muscles extensor of upper extremities decrease and tone of muscles
extensor of lower extremities increase. Turning of the head in right side add to the
change of tone of muscles extensor in the side of turhing the head. In this case
eyeballs are moving in the opposite side. All neck reflexes are polisynaptic.
Vestibular reflexes are static. Static reflexes of position provide supporting of
pose in the space.)
c) Conductive system (All nervous impulses from tracts of Goll's and
Burdach's about deep muscle-joint sensitivity transmit to cortex of big hemisphere.
Lateral corticospinalis tract begin from the big pyramidal cells of Bets and cross in
the hind-brain. To hind-brain go tractus corticobulbaris, which transmit impulses
from cortex to mooving nucleus of the cranial nerves. Substantia reticularis of
hind-brain give impulses to spinal cord.)
2. Mesencephalon (We mean that that mesencephalon is combain corpora
quadrigemina and pedunculi cerebri.)
a) Funtions, nuclei (Functions: reflectory, conductive. Nucleus of
mesencephalon: n. nervus oculumotorius, n. nervus trochlearis, substantia nigra,
nucleus ruber, nuclei substantia reticularis.)
b) Reflexes (The anterior quadrigeminal bodies are the primary optic centres
and involved in certain reflexes responding to light stimuli, including the visual
orientation reflexes. Reflex movements of the eyes are induced by impulses
conveyed to the eye musvles from the nuclei of the oculomotor and trochlear
nerves. The anterior quadrigeminal bodies take part in the pupillary reflexes. The
posterior quadrigeminal bodies are the primary auditory centres. They are involved
in the performance of sound orientation reflexes: the pricking up of the ears of
animals, turning of the head and body towards a new sound.
Vestibular reflexes are static and statokinetic. Static reflexes of straight
provide restore of pose. Statokinetic reflexes direct on supporting of pose in the
case of act the change of speed moving. These may be horizontal, vertical (in the
lift; increase tone of muscles extensor in the go up mowing and increase tone of
muscles flexor in the go down mowing and), angular.)
c) Conductive system (Fibres of the mid-brain connect cortex, mid-brain with
hind-brain and spinal cord. If the brain stem of a cat is severed above the medulla
oblongata so that the red nuclei are above the incision a special state of the body
musculature develops called decerebrate rigidity. This state is characterized by
sharply increased tone of the extensor muscles. The extremities are greatly
extended; the head is tilted back and the tail raised.)
3. Diencephalon (We mean that that diencephalon is combain thalamencephalon
and hypothalamus.)
a) Specific nuclei of thalamus (Specific nuclei have connection with the
projected zones of cortex. They are sensetive (geniculate bodies; transmit impulses
of tractus opticus, sound stimulus proprioreceptors of scin to the cortex) and motor
(transmit impulses to moving centres of cortex).
b) Associative nuclei of thalamus (Information are goes to them from periferal
parts and specific nuclei of thalamus. There are connections between nuclei and
zones. Associative nuclei of thalamus are sensory. For example, nucleus of pillow:
it lateral part transmits information about vision to associative zones of occipital
part, it medial part transmits information about hearing to associative zones of
temporal part of cortex.)
c) Nonspecific nuclei of thalamus (Their neurons are polysensetive. They give
the answers of excitement on any stimulus. They have high connection with
reticular formation, that's why the answers are in all part of the cortex.)
d) Morpho-funtional peculiarities of hypothalamus (Hypothalamus has 48
pairs of nucleus. According to the functional meaning, it may be divided on 3
parts: anterior, middle and posterior. Anterior part of hypothalamus produced two
kinds of substances: liberins and statins. Middle and posterior parts of
hypothalamus are zones without hematoencephalic baarrier. In these parts are
present neurons, which are sensetive to the change of temperature, chemical
components of blood.)
e) Role of hypothalamus in regulation of behavior (Anterior part of
hypothalamus is responsible for increase of muscle tone, aggression. Middle part
of hypothalamus is responsible for beggining of complex of somatic reactions,
which direct at search of water. Posterior part of hypothalamus is responsible for
beggining of complex of somatic reactions, which direct at search of food; in this
part present the centers of satisfaction.)
4. Physiological role of reticular formation of metecephalon, mesencephalon
(Most of the various sensory pathways relay impulses from sense organs via 3- and
4-neuron chains to particular loci in the cerebral cortex. The impulses are
responsible for perception and localization of individual sensations. Impulses in
these systems also relay via collaterals to the reticular activating system (RAS) in
the brain stem reticular formation. Activity in this system produces the conscious,
alert state that makes perception possible.
The reticular formation occupies the midventral portion of the medulla and
midbrain. It is made up of myriads of small neurons arranged in complex,
intertwining nets. Located within it are centers that regulate respiration, blood
pressure, heart rate, and other vegetative functions. In addition, it contains
ascending and descending components that play important roles in the adjustment
of endocrine secretion, the formation of conditioned reflexes, the regulation of
sensory input, and consciousness. The reticular activating system is a complex
polysynaptic pathway. Collaterals funnel into it not only from the long ascending
sensory tracts but also from the trigeminal, auditory, and visual systems and the
olfactory system. The complexity of the neuron net and the degree of convergence
in it abolish modality specificity, and most reticular neurons are activated with
equal facility by different sensory stimuli. The system is therefore nonspecific,
whereas the classic sensory pathways are specific in that the fibers in them are
activated only by one type of sensory stimulation. Part of the RAS by passes the
thalamus to project diffusely to the cortex. Another part of the RAS ends in the
intralaminar and related thalamic nuclei, and from them is projected diffusely and
nonspecifically to the whole neocortex. The RAS is intimately concerned with the
electrical activity of the cortex. It has inhibitory (excitement of the Rentshow cells
add to the inhibition of motoneurons; and direct inhibitory influences of
motoneurons of spinal cord) and excitive (increase tone of exrensor muscles,
contraction of sceletal muscles) influences.)
Key words and phrases: hind-brain, mid-brain, metencephalon,
mesencephalon, diencephalons, nuclei of trunk, conductive system, reflex activity,
specific associative and nonspecific nuclei of thalamus, reticular formation.
Theme 2
1. Structure-functional characteristic of the subcortical nucleus – basal ganglions
a) Components, functions (Physiologically, the basal ganglia are considered to
be comprised of the caudate nucleus, putamen, and globus pallidus. However, the
substantia nigra, subthalamus, and important portions of both the thalamus and
reticular formation operate in close association with these and therefore are
actually part of the basal ganglia system for motor control.
b) Afferent and efferent connection (
c) Circulation of excitement in the basal ganglion (cycle of putamen and
nucleus caudatum) (Function of the Caudate Nucleus and Putamen (The
Neostriatum). The caudate nucleus and putamen seem to function together to
initiate and regulate gross intentional movements of the body. To perform this
function they transmit impulses through two different pathways: (1) into the globus
pallidus, thence by way of the thalamus to the cerebral cortex, and finally
downward into the spinal cord through the corticospinal pathway; (2) downward
through the globus pallidus and the substantia nigra by way of short axons into the
reticular formation and finally into the spinal cord mainly through the
reticulospinal tracts.
In summary, the neostriatum helps control gross intentional movements that
we normally perform subconsciously. However, this control also involves the
motor cortex, with which the neostriatum is closely connected.)
d) Notion about extrapyramidal system
2. Functional assymetry of big hemispheres
a) Manifestations (somatic, sensory, psychological)
b) Methods of investigation
c) Practical meaning
3. Structure-functional characteristic of cerebellum (The cerebellum has long been
called a silent area of the brain principally because electrical excitation of this
structure does not cause any sensation and rarely any motor movement. However,
as we shall see, removal of the cerebellum does cause the motor movements to
become highly abnormal. The cerebellum is especially vital to the control of very
rapid muscular activities such as running, typing, playing the piano, and even
talking. Loss of this area of the brain can cause almost total incoordination of these
activities even though its loss causes paralysis of no muscles.
But how is it that the cerebellum can be so important when it has no direct
capability of causing muscle contraction? The answer to this is that it both helps
plan the motor activities and also monitors and makes corrective adjustments in the
motor activities elicited by other parts of the brain, It receives continuously
updated information on the desired program of muscle contractions from the motor
control areas of the other parts of the brain. And it receives continuous information
from the peripheral parts of the body to determine the instantaneous status of each
part of the body – its position, its rate of movement, forces acting on it, and so
forth. It is believed that the cerebellum compares the actual instantaneous status of
each part of the body as depicted by the peripheral information with the status that
is intended by the motor system. If the two do not compare favorably, then
appropriate corrective signals are transmitted instantaneously back into the motor
system to increase or decrease the levels of activation of the specific muscles.
Since the cerebellum must make major motor corrections extremely rapidly during
the course of motor movements, a very extensive and rapidly acting cerebellar
input system is required both from the peripheral parts of the body and from the
cerebral motor areas. Also, an extensive output system feeding equally as rapidly
into the motor system is necessary to provide the necessary corrections of the
motor signals.)
a) Afferent system (cells of cortex, afferent fibres, their cooporation)
b) Efferent system (nucleus, efferent connection)
c) Zones of cerebellum between cortex and nucleus
d) Functions and their neurons securing
FUNCTIONS OF THE BASAL GANGLIA
Before attempting to discuss the functions of the basal ganglia in human
beings, we should speak briefly of the better known functions of these ganglia in
lower animals. In birds, for instance, the cerebral cortex is poorly developed while
the basal ganglia are highly developed. These ganglia perform essentially all the
motor functions, even controlling the voluntary movements in much the same
manner that the motor cortex of the human being controls voluntary movements.
Further more, in the cat, and to a lesser extent in the dog, decortication removes
only the discrete types of motor functions and does not interfere with the animal's
ability to walk, eat, fight, develop rage, have periodic sleep and wakefulness, and
even participate naturally in sexual activities. However, if a major portion of the
basal ganglia is destroyed, only gross stereotyped movements remain, which were
discussed earlier in relation to the mesencephalic animal.
Finally, in the human being, cortical lesions in very young individuals destroy
the discrete movements of the body, particularly of the hands and distal portions of
the lower limbs, but do not destroy the person's ability to walk crudely, to control
equilibrium, or to perform many other subconscious types of movements.
However, simultaneous destruction of a major portion of the caudate nucleus
almost totally paralyzes the opposite side of the body except for a few stereotyped
reflexes integrated in the cord or brain stem.
With this brief background of the overall function of the basal ganglia, we can
attempt to dissect the functions of certain portions of the basal ganglia system,
realizing that the system actually operates, along with the motor cortex and
cerebellum, as a total unit and that individual functions cannot be ascribed to the
different individual parts of the basal ganglia.
Inhibition of Motor Tone by the Basal Ganglia. Though it is wrong to ascribe
a single function to all the basal ganglia, nevertheless, one of the general effects of
diffuse basal ganglia excitation is to inhibit muscle tone throughout the body. This
effect results from inhibitory signals transmitted from the basal ganglia to both the
motor cortex and the lower brain stem. Therefore, whenever widespread
destruction of the basal ganglia occurs, this causes muscle rigidity throughout the
body. For instance, when the brain stem is transected at the mesencephalic level,
which removes the inhibitory effects of the basal ganglia, the phenomenon of
decerebrate rigidity occurs.
Yet, despite this general inhibitory effect of the basal ganglia, stimulation of
certain specific areas within the basal ganglia can elicit positive muscle
contractions and at times even complex patterns of movements.
Function of the Globus Pallidus. It is alreadyclear that almost all the outflow
of signals from the basal ganglia are channelled through the globus pallidus en
route back to the cortex or on their way to lower brain centers. However, in
addition to this motor relay function of the globus pallidus, the globus pallidus
seems to have still another function that operates in close association with the
subthalamus and brain stem to help control the axial and girdle movements of the
body. These movements provide the background positioning of the body and
proximal limbs so that the more discrete motor functions of the hands and feet can
then be performed. That is, a person wishing to perform an exact function with a
hand first positions the body, next positions the legs and arms, and finally tenses
all the axial and girdle muscles to provide background positioning and stability of
all the proximal portions of the body. These associated tonic contractions are
supposedly initiated by circuits in the globus pallidus but operate also through the
axial and girdle motor control areas of the brain stem. Lesions of the globus
pallidus seriously interfere with the attitudinal movements that are necessary to
position the hand and, therefore, make it difficult or impossible for one to use the
hand for discrete activities.
Electrical stimulation of the globus pallidus while an animal is performing a
gross body movement often will stop the movement in a static position, the animal
holding that position for many seconds while the stimulation continues. This fits
with the concept that the globus pallidus is involved in some type of servo
feedback motor control system that is capable of locking the different parts of the
body into specific positions.
THE MOTOR CORTEX—THE PRIMARY AND PREMOTOR AREAS
The posterior part of this area, the somatic sensory cortex, we have already
discussed. Lying directly anterior to the somatic sensory area in front of the central
sulcus, as illustrated in the figure, and occupying approximately the posterior one
half of the frontal lobes is the motor cortex. Nerve signals originating from this
region cause muscle contractions in different parts of the body.
The motor cortex is divided into two separate divisions, the primary motor
area and the premotor area. The primary area contains very large pyramidal motor
neurons that send their fibers all the way to the spinal cord through the
corticospinal tract and therefore have almost direct communication with the
anterior motor neurons of the cord for control of either individual muscles or small
groups of muscles.
This area is frequently called areas VI and VIII because it occupies both these
areas in the Brodmann classification of brain topology. The premotor cortex has
very few neurons that project nerve fibers directly to the spinal cord. Instead, most
of the nerve signals generated in this area cause more complex muscle movements,
usually involving groups of muscles performing some specific task, rather than
individual muscles. To achieve these results, the premotor area mainly sends its
signals into the primary motor cortex to excite multiple groups of muscles. Some
of these signals pass directly to the motor cortex through subcortical nerve fibers,
but the premotor cortex also has extensive connections with the basal ganglia and
cerebellum, both of which transmit signals back by way of the thalamus to the
motor cortex. Thus the premotor cortex, the basal ganglia, the cerebellum, and the
primary motor cortex constitute a complex overall system for voluntary control of
muscle activity.
Key words and phrases: afferent and efferent connections; the circulation of
excitation; putamen cycle and the cycle of caudative nucleus; extrapyramidal
system; functional asymmetry of hemispheres; cortico-nuclear zones.
Theme 3
The functional part of the cerebral cortex is composed mainly of a thin layer of
neurons 2 to 5 millimeters in thickness, covering the surface of all the convolutions
of the cerebrum and having a total area of about one quarter square meter. The
total cerebral cortex probably contains 50 to 100 billion neurons.
Neurohistologists have divided the cerebral cortex into almost 100 different
areas, which have slightly different architectural characteristics. Yet in all these
different areas except the hippocampal region there still persist representations of
all the six major layers of the cortex.
FUNCTIONS OF CERTAIN SPECIFIC CORTICAL AREAS
Studies in human beings by neurosurgeons have shown that some specific
functions are localized to certain general areas of the cerebral cortex. Now present
a map of some of these areas as determined by Penfield and Rasmussen from direct
electrical stimulation of the cortex or by neurological examination of patients after
portions of the cortex had been removed. The lightly shaded areas are primary
sensory areas, while the darkly shaded area is the primary motor area (also called
voluntary motor area) from which muscular movements can be elicited with
relatively weak electrical stimuli. These primary sensory and motor areas have
highly specific functions as we have discussed in previous chapters, whereas other
areas of the cortex perform more general functions that we call association or
cerebration.
THE SENSORY ASSOCIATION AREAS
Around the borders of the primary sensory areas are regions called sensory
association areas or secondary sensory areas. In general, these areas extend 1 to 5
centimeters in one or more directions from the primary sensory areas; each time a
primary area receives a sensory signal, secondary signals spread, after a delay of a
few milliseconds, into the respective association area as well. Part of this spread
occurs directly from the primary area through subcortical fiber tracts, but part also
occurs in the thalamus, beginning in the sensory relay nuclei, passing next to
corresponding thalamic association areas, and then traveling to the association
cortex.
The general function of the sensory association areas is to provide a higher
level of interpretation of the sensory experiences.
Destruction of the sensory association area greatly reduces the capability of the
brain to analyze different characteristics of sensory experiences. For instance,
damage in the temporal lobe below and behind the primary auditory area in the
"dominant hemisphere" of the brain often causes a person to lose the ability to
understand words or other auditory experiences even though they are heard.
Likewise, destruction of the visual association area in Brodmann's areas 18 and
19 of the occipital lobe in the dominant hemisphere, or the presence of a brain
tumor or other lesion in these areas, does not cause blindness or prevent normal
activation of the primary visual cortex but does greatly reduce the person's ability
to interpret what is seen. Such a person often loses the ability to recognize the
meanings of words, a condition that is called word blindness or dyslexia.
Finally, destruction of the somatic sensory association area in the parietal cortex
posterior to primary somatic area I causes the person to lose spatial perception for
location of the different parts of the body. In the case of the hand that has been
"lost," the skills of the hand are greatly reduced. Thus, this area of the cortex seems
to be necessary for interpretation of somatic sensory experiences.
Possible Mechanisms for Attention and for Searching the Memory Store
We are all aware that we can direct our attention toward certain of our mental
activities individually and can also search through our memory store for specific
memories. Because of the capability of the generalized thalamocortical system to
activate small areas of the cerebral cortex at a time, it is tempting to believe that
specific activation of regional portions of the cortex might be the way in which we
do indeed direct our attention, and might also be the basis for searching through
memory stores.
One other bit of information also suggests that the generalized thalamocortical
system might be important in searching for memories: It has been reported that
specific lesions in the thalamus are sometimes associated with retrograde amnesia
– that is, inability to recall memories that are known to be stored within the brain.
BRAIN WAVES
Electrical recordings from the surface of the brain or from the outer surface of
the head demonstrate continuous electrical activity in the brain. Both the intensity
and patterns of this electrical activity are determined to a great extent by the
overall level of excitation of the brain resulting from functions in the reticular
activating system. The undulations in the recorded electrical potentials, are called
brain waves, and the entire record is called an electroencephalogram (EEG).
The intensities of the brain waves on the surface of the scalp range from 0 to
300 microvolts, and their frequencies range from once every few seconds to 50 or
more per second. The character of the waves is highly dependent on the degree of
activity of the cerebral cortex, and the waves change markedly between the states
of wakefulness and sleep and coma.
Much of the time, the brain waves are irregular, and no general pattern can be
discerned in the EEG. However, at other times, distinct patterns do appear. Some
of these are characteristic of specific abnormalities of the brain, such as epilepsy,
which is discussed later. Others occur even in normal persons and can be classified
as alpha, beta, theta, and delta waves.
Alpha waves are rhythmic waves occurring at a frequency of between 8 and 13
per second and are found in the EEGs of almost all normal adult persons when they
are awake in a quiet, resting state of cerebration. These waves occur most intensely
in the occipital region but can also be recorded at times from the parietal and
frontal regions of the scalp. Their voltage usually is about 50 microvolts. During
sleep the alpha waves disappear entirely, and when the awake person's attention is
directed to some specific type of mental activity, the alpha waves are replaced by
asynchronous, higher frequency but lower voltage beta waves. Note that the visual
sensations cause immediate cessation of the alpha waves and that these are
replaced by low voltage, asynchronous beta waves.
Beta waves occur at frequencies of more than 14 cycles per second and as high
as 25 and rarely 50 cycles per second. These are most frequently recorded from the
parietal and frontal regions of the scalp. Most beta waves appear during activation
of the central nervous system or during tension.
Theta waves have frequencies of between 4 and 7 cycles per second. These
occur mainly in the parietal and temporal regions in children, but they also occur
during emotional stress in some adults, particularly during disappointment and
frustration. They can often be brought out in the EEG of a frustrated person by
allowing enjoyment of some pleasant experience and then suddenly removing this
element of pleasure; this causes approximately 20 seconds of theta waves. These
same waves also occur in many brain disorders.
Delta waves include all the waves of the EEG below 3.5 cycles per second and
sometimes as low as 1 cycle every 2 to 3 seconds. These occur in deep sleep, in
infancy, and in serious organic brain disease. And they occur in the cortex of
animals that have had subcortical transections separating the cerebral cortex from
the thalamus. Therefore, delta waves can occur strictly in the cortex independently
of activities in lower regions of the brain. Physiologic diagnosis of functional state
of mechanisms of regulation in general and particular regulative zones, to realize
the functions of cortex of encephalon as the highest regulative CNS level.
Key words and phrases: neuron layer, corticolisation of functions, primary
zone, motor zone, premotor zone, additional motor zone, somato-sensor zone, optic
zone, olfactory zone, zone of taste, associative zones, electrocorticography,
electroencephalography.
Students must know:
Theme 1
1. Structure and functions of hind-brain; mesencephalon; thalamus and
hypothalamus.
2. Physiological role of reticular formation.
Theme 2
1. Morphological and functional characteristics of the Basal Ganglia and
cerebellum.
Theme 3
1. Morpho- functional characteristics of cortex of encephalon
a) Functions
b) Neurons lyers
c) Corticalization of functions
2. Projective zones
a) Primary motor zone
b) Premotor zone
c) Additive motor zone
d) Primary and secondary somatosensor zones
e) Zone of vision
f) Hearing, testing, smelling zones
j) Column organization
3. Associative zone
a) Peculiarities
b) Physiological meaning
4. Investigation of electrical phenomenon in cortex of big hemispheres
a) Electrocorticography
b) Elecrtoencephalography
Students should be able to:
Theme 1
To induce: superciliar, lid and mandibular reflexes.
Theme 2
1. Cerebellum tests
2. Displays of functional encephalic asymetry.
Theme 3
1. Register electroencephalogram
Tests and assignments for Self-assessment
Multiple Choice.
Choose the correct answer/statement:
Theme 1
1. Where should you make the transaction of the brain to cause the rigidity?
a) upper the red nucleus; b) under the red nucleus; c) under vestibular
nucleus;
d) under the nucleus of Yakubovych; e) under the nucleus of Deyters.
2.Where are the reflex arcs of orientative reflexes situated?
a) the red nucleus; b) quadrigeminal body; c) the black substance;
d) nuclei of mesencephalon; e) nucleus of Yacubovych-Vestfal-Triger.
Real-life situation to be solved:
1. It was found that during the intake of pharmacological substances, which
blockade the structures of reticular formation of the trunk of the brain, bioelctric
and functional activity of the cortex of brain inhibit intensively. Why does it
happen? What is the mechanism relaxation in this case?
Answers for the Self-control
1. b; 2. b;
1. The transmission of excitation throughout the ascending reticulo-cortical ways
which relize an activate influences to the neurons of encephalon cortex.
Theme 2
1. Which layers are present in cerebellum?
a) Molecular, fastigial, Purkinje cell; b) Molecular, stellate, Bets cell; c)
Molecular, dentate, Purkinje cell; d) Globose, stellate, Purkinje cell; e) Molecular,
stellate, Purkinje cell.
Real-life situations to be solved:
1. While studying the functions of different parts of central nervous system, one of
the students while extracting the part of brain of a rat, made a wrong move which
resulted in disappearing of some right side reflexes, like moving round the circle.
Which part of the brain was distroyed?
III. Answers for the Self-Control
1. e;
1. Cerebellum.
Theme 3
1. On EEG of patient G. determine alpha-rythm. Which parameters of EEG
characterozed alpha rethm?
a) frequency – 18 Gerths, amplitude – 50 mcV; b) frequency – 24 Gerths,
amplitude – 25 mcV; c) frequency – 12 Gerths, amplitude – 50 mcV; d) frequency
– 9 Gerths, amplitude – 20 mcV; e) frequency – 2 Gerths, amplitude – 25 mcV.
2. On EEG of patient P. determine beta-rythm. Which parameters of EEG
characterozed beta-rethm?
a) frequency – 18 Gerths, amplitude – 50 mcV; b) frequency – 24 Gerths,
amplitude – 25 mcV; c) frequency – 12 Gerths, amplitude – 50 mcV; d) frequency
– 9 Gerths, amplitude – 20 mcV; e) frequency – 2 Gerths, amplitude – 25 mcV.
Real-life situation to be solved:
1. While analizing of the EEG of the student the frequency of periodic potential of
12/sec and the altitude of 5 microvolts were found.
a) What rhythm do these parameters refer to?
b) In what conditions was the student during the registration of EEG?
III. Answers for the Self-control
1. c; 2. b;
1. a) α–rhythm;
b) physical and emotional peace.
References:
1. Review of Medical Physiology // W.F.Ganong. – Twentieth edition, 2001. – P.
198-216., 224-225.
2. Textbook of Medical Physiology // A.C.Guyton, J.E.Hall. – Tenth edition, 2002.
– P. 514, 634. 659, 663-671.
Methodical Instructions to Lesson 10 for Students
Theme: FUNCTIONAL PECULIARITIES OF AUTONOMIC (Vegetative)
NERVOUS SYSTEM.
Aim: To know the peculiarities of autonomic nervous system; be able to use this
knowledge on practice.
Professional Motivation: The knowledge of physiology of autonomic nervous
system is necessary for prospective physicians for diagnosis of different diseases.
Basic Level:
1. Structure of autonomic nervous system (Anatomy Course)
Students` practical Activities:
Influence of parasympathetic nervous system on the heart activity
To narcotize a rat and fix it on the preparative table. To make the middle cut on
the neck. Find and to separate nervus vagus. Registrate the ECG before and after
the electric stimulation of the nerve. Compare the frequency of the heart
contraction before and after stimulation of the nerve. Show the results of the
investigation in your notebooks.
In conclusion define the influence of parasympathetic nervous system on the
heart activity.
Students’ Independent Study Program
I. Objectives for Students’ Independent Studies
You should prepare for the practical class the existing textbooks and lectures.
Special attention should be paid to the following:
1. Morpho-functional organization of autonomic nervous system
a) Sympathetic nervous system (Sympathetic patr of autonomic nervous system
includes paravertebral ganglions, prevertebral ganglions, sympathetic nerves. In
the lateral parts of the spinal cord on the thoracic-lumbal level are present
sympathetic centre of Yakobson, whose activity regulated by brain stem. Axons of
neurons of sympathetic centre go out from the spinal cord in ventral roots and form
white branches with the ganglions of sympathetic stems. From these stems go out
postganglionic axons and go to the organs of brain, thorax, abdominal cavity and
pelvis. Preganglionic axons, which goes out on the level of segments of spinal
cord, innerevate a few paravertebral and prevertebral ganglions; that is why
provide multiplicative central regulation of different visceral functions.
b) Parasympathetic nervous system (Parasympathetic patr of autonomic
nervous system includes ganglions (present near organs-effectors or inside them),
parasympathetic nerves. Bodies of the preganglionic parasympathetic neurons are
in the brain stem and in the sacral level of spinal cord. Axons of preganglion
neurons go to the postganglion neurons, which are present in ganglions. The
parasympathetic fibers are in n.oculomotorius, n.facialis, n.glossopharyngeus,
n.vagus, sacral nerves. Parasympathetic nervous system also innervates muscles of
vessels, exept sex organs and may be brain.)
c) Metasympathetic nervous system (Metasympathetic patr of autonomic
nervous system is intramural ganglions, which are in the organs walls. Reflector
arc are present in the wall of organs too. It regulated by sympathetic and
parasympathetic system. It has sensory, interneuronal, moving chain and own
mediators.)
2. Characteristic of reflector arc of autonomic nervous system
a) Sensory part (Receptors are present in inner organs, walls of blood vessels
and lymphatic vessels of skin, muscles. They named interoreceptors. Their
stimulus: mechanical, chemical, and temperature irritans. Afferent part of
autonomic reflex consists of interoreceptors, dendrites of sensory neurons, which
are in autonomic and spinal ganglions.
From interoreceptors afferent informations enter to sensitive neurons, whose
body are in autonomic and spinal ganglions. So, in afferent part of autonomic
reflex, sensitive information transmit in two ways: 1) from interoreceptors to
sensitive neurons of spinal ganglions of dorsal roots of spinal cord; 2) from
interoreceptors to sensitive neurons of autonomic ganglions of dorsal, and then to
sensitive neurons of spinal ganglion of posterior roots. From spinal ganglions,
transmitters of autonomic sensitivity enter in spinal cord. Signal from
interoreceptors may enter in brain pass spinal cord. Crossing of afferent signals on
interneurons is on spinal' and bulbar' level.)
b) Central part (Spinal level. When the neurons enter in spinal cord one part of
the afferent fibers interact with segmental interneurons, which interact with
preganglionic neurons. This is polysynaptic arc. Part of the afferent fibers end in
grey substance of upper segments and medulla oblongata. Part of the afferent fibers
lower and connect by synapses with interneurons of lower segments.
Supraspinal level. Then the afferent signals go to reticular formation of brein
stem. Interaction of afferent visceral and somatic signals activates reticular
formation. From reticular formation descending signals transmit to preganglion
neurons of arc of autonomic reflex. Ascending signals transmited to mid-brain,
dyencephalon, cortex.
c) Efferent part. Peculiarities of mediator transmition in efferent part of
autonomic nervous system (scheme):
Transmission at the synaptic junctions between pre- and postganglionic
neurons and between the postganglionic neurons and the autonomic effectors is
chemically mediated. The principal transmitter agents involved are acetylcholine
and norepinephrine, although dopamine is also secreted by intemeurons in the
sympathetic ganglia.
Preganglionic
neuron
Parasympathetic
nervous
system
Sympathetic
nervous
system
Еxtramural
ganglion
Еffector
Аch N-chr
Аch
M-chr
Аch N-chr
Catecholamines,
AR
Аch N-chr
Аch N-chr
N-chr (sweet glands,
vessels of muscles)
Epi
Nor
blood
Adrenal glands
d) Difference between autonimuc and somatic nervous system (1. Nervous
centres in autonimuc nervous system are present in mesencephalon, bulbar part of
brain, thoraco-lumbal and sacral part of spinal cord, in somatic – diffuse in all
sentral nervous system; 2. Efference ways of reflector arc in autonimuc nervous
system consist of two neurons, in somatic – of one; 3. In analysing of information
in autonimuc nervous system take part ganglions, in somatic – nervous centres; 4.
Exit of nervous fibers from central nervous system autonimuc nervous system is
mix, in somatic – segmental; 5. Mediators of autonimuc nervous system are
acetylcholine, epinephrine, norepinephrine, ATP, serotonine, gistamine, substance
P, of somatic – only acethylcholine; 6. Functions of autonimuc nervous system are
growth, work of inner organs, supporting of homeostasis. of somatic – providing
moving reactions of sceletal muscles and sensitive outer stimulus; 7. Effect in
autonimuc nervous system may be as excitive, as inhibit, in somatic – only
excitive.
3. Change of functional condition of organs in the case of stimulation of autonomic
nerves
Symptoms
Sympathetic effecrs
Parasympathetic effecrs
Pupil of eye
Increase
Normal or decrease
Cardiovascular system:
heart beat
Increase
Decrease
strength
of
cardiac Increase
Decrease
contractility
Rate of breathing
Normal or increase
Decrease
Diameter of bronchs
Increase
Decrease
Digestive tract:
Salivation
Increase, viscous saliva
Increase, liguid saliva
Motility
Secretory function
Sphincters
Vessels of sceletal muscles
Vessels of skin
Sweet glands
Decrease
Decrease
Contract
Increase
Decrease
Secretion
Increase
Increase
Relex
–
–
–
Key words and phrases: Sympathetic Nervous System, Parasympathetic Nervous
System, Metasympathetic Nervous System, sensitive branch, central branch,
efferent branch.
Students must know the peculiarities of:
1. Sympathetic nervous system
2. Parasympathetic nervous system
3. Metasympathetic nervous system
Tests and assignments for Self-assessment
Multiple Choice.
Choose the correct answer/statement:
1. Patient S. has complete on increasing of breathing frequency, heart beat. Which
another complets may be in the patient if we know that he has irritation of
sympatetic nervous system?
a) Increase salivation, liguid saliva; b) Relaxation of sphincters; c) Increase
motility of digestive tract; d) Increase secretion of digestive tract; e) Decrease
strength of cardiac contractility.
Real-life situation to be solved:
1. Patient R. has problem in the thoracic level of vertebrum. Which compleate he
has?
Answers for the Self-control
1. a;
1. He has the problem of irritation of sympathetic nervous system.
References:
1. Review of Medical Physiology // W.F.Ganong. – Twentieth edition, 2001. – P.
217-223.
2. Textbook of Medical Physiology // A.C.Guyton, J.E.Hall. – Tenth edition, 2002.
– P. 697-707.
Methological Instructions to lesson 11 for students
Themes:
1. ROLE OF THE AUTONOMIC ( VEGETATIVE ) NERVOUS SYSTEM
IN REGULATION OF VISCERAL FUNCTIONS.
2. CENTRAL REGULATION OF VEGETATIVE FUNCTIONS OF THE
ORGANISM.
Aim: To know the role of vegetative nervous system in regulation of homeostasis.
To realize the peculiarities of central regulation of vegetative functions of the
organism by spinal, bulbar, mesencephal, diencephal, cortical levels.
Professional Motivation: The knowledge of role of vegetative nervous system is
necessary for future physicians to value the functional condition of organs. The
knowledge of central regulation of vegetative functions of the organism is
necessary for future physicians to value the condition of whole organism.
Basic Level:
1. Structure of vegetative nervous system/ Structure of the regulative levels
(Department of Anatomy).
2. Microstructure of the regulative levels of CNS (Department of Histology).
Students` Practical Activities:
Theme 1
Cold test:
Count the frequency of pulse on the one of the hand. Put the arm of another
hand into the лоток of cold water (+14 Co) for 3 minutes and every 30 seconds
count the frequency of pulse. After 2 minutes take out the hand. The result of
experiment show graphically.
Hot test:
Count the frequency of pulse on the one of the hand. Put the arm of another
hand into the лоток of warm water (+45 Co) for 3 minutes and every 30 seconds
count the frequency of pulse. After 2 minutes take out the hand. The result of
experiment show graphically.
In conclusion define, what vegetative reflexes are in base of the tests and what
parts of autonomic nervous system dominate in regulation of heart activity.
Theme 2
Pilomotor reflex.
To make a thermal (ice) or mechanical stimulus of skin in area of trapezoidal
muscle. Pay attention on development of anserine skin on the part of the body.
Rise of intensive anserine skin on the whole body testifies of increased of irritation
of the sympathetic nervous system (slight anserine skin testifies of normal
reaction). It is known, that pileous muscles of head and neck are connected with I-
III thoracic segments, pileous muscles of hands are connected with IV-VII thoracic
segments, pileous muscles of trunk are connected with VIII-IX thoracic segments.
In conclusion define, what the results testify.
Functional significance of posterior hypothalamus (stereotaxic research).
To determine stereotaxic coordinates of posterior hypothalamus. To narcotize a
rat and fix it on a table. Put the identeferentive electrode into the cervic muscles of
a rat. The active electrode into the electrodo-holder and lead it into the posterior
hypothalamus.
To count a quantity of respiratorical movements during one minute. To make
the stimulation and then count a quantity of respiratorical movements once more.
Put the results into the chart:
Quantity of respiratorical movements
before the stimulation
after the stimulation
In conclusion define, why has the respiration been changed during the
stimulation of posterior hypothalamus.
Students’ Independent Study Program
Theme 1
Objectives for Students’ Independent Studies
You should prepare for the practical class the existing textbooks and lectures.
Special attention should be paid to the following:
Theme 1
RESPONSES OF EFFECTOR ORGANS TO AUTONOMIC NERVE IMPULSES
General Principles
The smooth muscle in the walls of the hollow viscera is generally innervated by
both noradrenergic and cholinergic fibers, and activity in one of these systems
increases the intrinsic activity of the smooth muscle whereas activity in the other
decreases it. However, there is no uniform rule about which system stimulates and
which inhibits. In the case of sphincter muscles, both noradrenergic and
cholinergic innervations are excitatory, but one supplies the constrictor component
of the sphincter and the other the dilator.
There is usually no acetylcholine in the circulating blood, and the effects of
localized cholinergic discharge are generally discrete and of short duration because
of the high concentration of acetylcholinesterase at cholinergic nerve endings.
Norepinephrine spreads farther and has a more prolonged action than
acetylcholine. The epinephrine and some of the dopamine come from the adrenal
medulla, but much of the norepinephrine diffuses into the bloodstream from noradrenergic nerve endings.
Cholinergic Discharge
In a general way, the functions promoted by activity in the cholinergic division
of the autonomic nervous system are those concerned with the vegetative aspects
of day-to-day living. For example, cholinergic action favors digestion and
absorption of food by increasing the activity of the intestinal musculature,
increasing gastric secretion, and relaxing the pyloric sphincter. For this reason, and
to contrast it with the ''catabolic'' noradrenergic division, the cholinergic division is
sometimes called the anabolic nervous system.
Noradrenergic Discharge
The noradrenergic division discharges as a unit in emergency situations. The
effects of this discharge are of considerable value in preparing the individual to
cope with the emergency, although it is important to avoid the teleologic fallacy
involved in the statement that the system discharges in order to do this. For
example, noradrenergic discharge relaxes accommodation and dilates the pupils
(letting more light into the eyes), accelerates the heartbeat and raises the blood
pressure (providing better perfusion of the vital organs and muscles), and constricts
the blood vessels of the skin (which limits bleeding from wounds). Noradrenergic
discharge also leads to lower thresholds in the reticular formation (reinforcing the
alert, aroused state) and elevated blood glucose and free fatty acid levels
(supplying more energy). On the basis of effects like these, Cannon called the
emergency-induced discharge of the noradrenergic nervous system the ''preparation
for flight or fight.''
The emphasis on mass discharge in stressful situations should not obscure the fact
that the noradrenergic autonomic fibers also subserve other functions. For
example, tonic noradrenergic discharge to the arterioles maintains arterial pressure,
and variations in this tonic discharge are the mechanism by which the carotid sinus
feedback regulation of blood pressure is effected. In addition, sympathetic
discharge is decreased in fasting animals and increased when fasted animals are
refed. These changes may explain the decrease in blood pressure and metabolic
rate produced by fasting and the opposite changes produced by feeding.
Key words and phrases: vegetative reflexes: viscero-visceral, viscerodermal, dermato-visceral, tonic activity of vegetative nervous system.
Theme 2
MEDULLA OBLONGATA
Control of Respiration, Heart Rate, & Blood Pressure
The medullary centers for the autonomic reflex control of the circulation, heart,
and lungs are called the vital centers because damage to them is usually fatal. The
afferent fibers to these centers originate in a number of instances in highly
specialized visceral receptors. The specialized receptors include not only those of
the carotid and aortic sinuses and bodies but also receptor cells that are apparently
located in the medulla itself. The motor responses are graded and delicately
adjusted and include somatic as well as visceral components.
Other Medullary Autonomic Reflexes
Swallowing, coughing, sneezing, gagging, and vomiting are also reflex
responses integrated in the medulla oblongata. Coughing is initiated by irritation of
the lining of the respiratory passages. The glottis closes and strong contraction of
the respiratory muscles builds up intrapulmonary pressure, whereupon the glottis
suddenly opens, causing an explosive discharge of air. Sneezing is a somewhat
similar response to irritation of the nasal epithelium. It is initiated by stimulation of
pain fibers in the trigeminal nerves.
RELATION OF HYPOTHALAMUS TO AUTONOMIC FUNCTION
Many years ago, Sherrington called the hypothalamus "the head ganglion of the
autonomic system." Stimulation of the hypothalamus produces autonomic
responses, but there is little evidence that the hypothalamus is concerned with the
regulation of visceral function per se. Rather, the autonomic responses triggered in
the hypothalamus are part of more complex phenomena such as rage and other
emotions.
"Parasympathetic Center"
Stimulation of the superior anterior hypothalamus occasionally causes
contraction of the urinary bladder, a parasympathetic response. Largely on this
basis, the statement is often made that there is a "parasympathetic center " in the
anterior hypothalamus. However, bladder contraction can also be elicited by
stimulation of other parts of the hypothalamus, and hypothalamic stimulation
causes very few other parasympathetic responses. Thus, there is very little
evidence that a localized "parasympathetic center" exists. Stimulation of the
hypothalamus can cause cardiac arrhythmias, and there is reason to believe that
these are due to simultaneous activation of vagal and sympathetic nerves to the
heart.
Sympathetic Responses
Stimulation of various parts of the hypothalamus, especially the lateral areas,
produces a rise in blood pressure, pupillary dilatation, piloerection, and other signs
of diffuse noradrenergic discharge. The stimuli that trigger this pattern of
responses in the intact animal are not regulatory impulses from the viscera but
emotional stimuli, especially rage and fear. Noradrenergic responses are also
triggered as part of the reactions that conserve heat.
Low-voltage electrical stimulation of the middorsal portion of the
hypothalamus causes vasodilatation in muscle. Associated vasoconstriction in the
skin and elsewhere maintains blood pressure at a fairly constant level. This
observation and other evidence support the conclusion that the hypothalamus is a
way station on the so-called cholinergic sympathetic vasodilator system, which
originates in the cerebral cortex. It may be this system, which is responsible for the
dilatation of muscle blood vessels at the start of exercise.
Stimulation of the dorsomedial nuclei and posterior hypothalamic areas
produces increased secretion of epinephrine and norepinephrine from the adrenal
medulla. Increased adrenal medullary secretion is one of the physical changes
associated with rage and fear and may occur when the cholinergic sympathetic
vasodilator system is activated. It has been claimed that there are separate
hypothalamic centers for the control of epinephrine and norepinephrine secretion.
Differential secretion of one or the other of these adrenal medullary
catecholamines does occur in certain situations, but the selective increases are
small.
ANATOMIC CONSIDERATIONS
The term limbic lobe or limbic system is applied to the part of the brain that
consists of a rim of cortical tissue around the hilus of the cerebral hemisphere and a
group of associated deep structures – the amygdala, the hippocampus, and the
septal nuclei. The region was formerly called the rhinencephalon because of its
relation to olfaction, but only a small part of it is actually concerned with smell.
LIMBIC FUNCTIONS
Stimulation and ablation experiments indicate that in addition to its role in
olfaction, the limbic system is concerned with feeding behavior. Along with the
hypothalamus, it is also concerned with sexual behavior, the emotions of rage and
fear, and motivation.
Autonomic Responses & Feeding Behavior
Limbic stimulation produces autonomic effects, particularly changes in blood
pressure and respiration. These responses are elicited from many limbic structures,
and there is little evidence of localization of autonomic responses. This suggests
that the autonomic effects are part of more complex phenomena, particularly
emotional and behavioral responses. Stimulation of the amygdaloid nuclei causes
movements such as chewing and licking and other activities related to feeding.
Lesions in the amygdala cause moderate hyperphagia, with indiscriminate
ingestion of all kinds of food.
Key words and phrases: vegetative centers, posterior hypothalamus, anterior
hypothalamus, autonomic regulation of diuresis, vegetative regulation of
defecation, vegetative regulation of sexual reflexes, limbic system.
Students must know:
Theme 1
1. Vegetative reflexes.
2. The importance of sympathetic and parasympathetic nervous systems.
3. Autonomic reflexes
a) viscero-visceral
b) viscero-dermal (viscero-somatic)
c) dermato-visceral (somato-visceral)
4. Role of autonomic nervous system in supporting of organism' vital activity
a) Meaning of sympathetic nervous system
b) Role of parasympathetic nervous system
c) Meaning of meta sympathetic nervous system
d) Tonic activity of autonomic nervous system
Theme 2
1. Role of spinal cord, hind-brain, mid-brain in regulation of vegetative functions
a) Autonomic centers of spinal cord
b) Autonomic regulation of micturation
c) Autonomic regulation of defecation
d) Autonomic regulation of sex reflexes
2. Role of hypothalamus in regulation of autonomic functions
a) Physiological meaning of posterior hypothalamus
b) Role of anterior hypothalamus
c) Meaning of middle hypothalamus
3. Role of limbic system and cortex of big hemispheres in regulation of autonomic
functions
Students should be able to:
1. To make cool and thermal tests.
2. To make a pilomotor reflex.
Tests and Assignments for Self-assessment
Multiple Choice.
Choose the correct answer/statement:
Theme 1
1. Patient T. has inflamation of appendicular vermiformies. Which somatic
manifistation of viscero-somatic reflex he has?
a) Pain and contraction of all abdominal muscles; b) Pain of muscles above
place of inflamation; c) Pain and contraction of legs muscles; d) Pain and
contraction of muscles above place of inflamation; e) Pain and contraction of all
muscles.
Real-life situation to be solved:
1. Student U. after running has increasing of heart beat and pain in right epigastral
area. Which kind of autonomic reflex he has?
Answers for the Self-control
1. d;
1. This reflex is viscero-visceral.
Theme 2
1. Patient F. has tumor of anterior stereotaxis. Which heart beart he has?
a) 54 per minute; b) 60 per minute; c) 78 per minute; d) 90 per minute; e)
104 per minute.
Real-life situation to be solved:
1. During the experiment the stimulation of anterior hypotalamus of the rat was
held.
a) What methods did you use?
b) What are reactions of cardiovascular, respiratorical and digestive systems did
you see. Explain, please.
Answers for the Self-control
1. a;
1. a) Stereotaxis methods.
b) Decreasing of the frequency and power of the contraction of the heart, stenosis
of bronchi, motility secretion and absorption in digestive tract. Parasympathetic
influences.
References:
1. Review of Medical Physiology // W.F.Ganong. – Twentieth edition, 2001. – P.
217-223, 226-229, 232-233, 242.
2. Textbook of Medical Physiology // A.C.Guyton, J.E.Hall. – Tenth edition, 2002.
– P. 364, 632, 681-684, 697-707, 736.
Methological instruction to lesson 6 for students
Themes:
1.
REGULATION
OF
PHYSIOLOGICAL
FUNCTIONS
BY
HYPOTHALAMIC-HYPOPHYSIS
SYSTEM
AND
EPINEPHRAL
GLANDS.
2. THE ROLE OF GLANDS IN THE REGULATION OF ORGANISM
FUNCTIONS
3. AGED PECULIARITIES OF NEURAL AND HUMORAL
REGULATION.
Aim: To know the mechanism of regulation of physiological functions by
hypothalamic-hypophysis system and epinephral glands. To know the peculiarities
of regulation of organism functions by glands. To understand the meaning of
hormones and their influence on the metabolism of cells and organs. To know the
aged peculiarities of neural and endocrine regulation in fetus, newborn, children
and old persons.
Professional motivation: The knowledge of these processes is important for
physicians in diagnostics of hormonal discharges and treatment of them. The
knowledge of hormones role in the organism is necessary for prospective
physicians for understanding the changes of organism functions in different
situations and for diagnosis of different diseases. The knowledge of aged
peculiarities of neural and endocrine regulation in fetus, newborn, children and old
persons are necessary for future physicians to value the peculiarities diseases in
pediatric and geriatric clinics.
Basic level:
1. Structure of hypothalamus, hypophysis and epinephral glands. Localisation of
glands in the human organism (Department of Anatomy).
2. Microstructure of hypothalamus, hypophysis and epinephral glands.
Microstructure of glands (Department of Histology).
3. Hormones of hypothalamic-hypophysis system and epinephral glands
(Department of Biology).
4. Hormones (department of Biochemistry).
Students` practical Activities:
Theme 1
Influence of melanocyte stimulating hormone on pigment cells of swimming
membrane of a frog.
Fix a narcotized frog on a table. Stretch the swimming membrane above the
hole of the t.able and observe it under the small magnification of a microscope.
Pay attention to the condition of pigment cells. Introduce 0,2 ml of melanocyte
stimulating hormone into spinal lymphatic sack. Evaluate the color of the animal
and the condiiton of pigment cells in 20 min. Draw what you’ve observed under
the microscope before and after the introduction of melanocyte stimulating
hormone in your protocols.
In conclusion define what is the influence of melanocyte stimulating hormone.
The influence of epinephrine on the size of pupilla
Compare the diameter of pupilla in both eyes of the examinie. Than put 1-2
drops of epinephrine 0,1% into conjuctival sack. Observe the size of pupillas
during 20-30 minutes. Picture the observed changes schematically.
In conclusion define the mechanism of observed changes.
Theme 2
Evaluation of the parathyroid glands condition
a) Chvostek’s test
Make some light knockings by a neurological hammer in front of meatus
acustius externus. If the functions of parathyroid glands are damaged the
contraction of the muscles that are innervated by the VII nerve is observed.
b) Veis’ test
Make some light knockings on the lateral margin of the orbita where there is a
zygomatical branch of the nervus facialis. If the functions of parathyroid glands are
damaged the contraction of the musculus orbicularis oculi is observed.
c) Trusso’s test
Press the brachium by turniquet pulse will disappear for 2-3 minutes. If the
functions of parathyroid glands are damaged the titanic contraction of manual
muscles is observed.
In conclusion define the functional state of parathyroid glands of the patient.
Influence of the insulin on the glucose adoption
Take two white mice with the same weight. Introduce intraperitoneal 1.5-2.0 ml
of 20 % glucose solution. Give subcutaneal insulin to one mouse. To pick up the
urine during one hour.
Make an investigation of the urine for the glucose. Filtrate 3 ml urine. Make a
Feling’s reaction for the glucose. Compare the resultates.
In conclusion define the influence of the insulin on the glucose adoption.
Theme 3
Age peculiarities of hematoencephalic barrier
There were studied the changes of brain sensitivity to acetylcholine in animals of
different age under the influence of hypoxia. Investigations were held on 45 rats of
4-5 months. Control was grown-up rats. In all experiments they registrated
electrocorticogram. Acetylcholine was introduces into common jugular vein. On
the electrocorticogram they noticed the presence or absense of reaction of cortical
biorhythms on the acetylcholine introducing. There was found higher brain
sensitivity to acetylcholine in young rats comparing to grown-up rats. It is known
that during intraarterial and intraventtricular introduction acetylcholine causes
exact changes in EEG. This fact was first described be Bonne and Bremer,
Morutsi, and then ensured by many scientific works. The question about activating
influence of acetylcholine during intravenous introduction is not sure, because it is
known that acetylcholine goes badly through the hematoencephalic barrier. In our
experiments electrocortical reaction in intravenous introduction of acetylcholine
was noticed only in 20 % of experiments under grown-up animals. At the same
time in young rats it was observed more often – in 78 % of cases. The duration of
electrocortical reactions in grown-up rats was shorter than in animals of younger
age. More often appearance of brain cortex reaction in young rats in comparison to
grown-ups can be explained by higher penetration of hematoencephalic barrier in
young rats. Grashchenkov and Kassil noticed that due to high penetration of
hematoencephalic barrier in young age hemoreactivic brain formations in children
react on changes in composition and properties of internal environment easier and
faster than in adults.
Students’ Independent Study Program
І Objectives for Students` Independent Studies:
You should prepare for the practical class the existing textbooks and lectures.
Theme 1
Anterior Pituitary Hormones.
(1) Growth hormone: causes growth of almost all cells and tissues of the body.
(2) Adrenocorticotropin: causes the adrenal cortex to secrete adrenocortical
hormones.
(3) Thyroid-stimulating hormone: causes the thyroid gland to secrete thyroxine
and triiodothyronine.
(4) Follicle-stimulating hormone: causes growth of follicles in the ovaries prior
to ovulation, promotes the formation of sperm in the testes.
(5) Luteinizing hormone: plays an important role in causing ovulation; also
causes secretion of female sex hormones by the ovaries and testosterone by the
testes.
(6) Prolactin: promotes development of the breasts and secretion of milk.
Posterior Pituitary Hormones.
(1) Antidiuretic hormone (also called vasopressin): causes the kidneys to retain
water, thus increasing the water content of the body; also, in high concentrations,
causes constriction of the blood vessels throughout the body and elevates the blood
pressure.
(2) Oxytocin: contracts the uterus during the birthing process, thus perhaps
helping expel the baby; also contracts myoepithelial cells in the breasts, thereby
expressing milk from the breasts when the baby suckles.
Adrenal Cortex.
(1) Cortisol: has multiple metabolic functions for control of the metabolism of
proteins, carbohydrates, and fats.
(2) Aldosterone: reduces sodium excretion by the kidneys and increases
potassium excretion, thus increasing sodium in the body while decreasing the
amount of potassium.
From this overview of the endocrine system, it is clear that most of the
metabolic functions of the body are controlled one way or another by the endocrine
glands. For instance, without growth hormone, the person remains a dwarf.
Without thyroxine and triidothyronine from the thyroid gland, almost all the
chemical reactions of the body become sluggish, and the person becomessluggish
as well. Without insulin from the pancreas, the body's cells can utilize very little of
the food carbohydrates for energy. And, without the sex hormones, sexual
development and sexual functions are absent.
CHEMISTRY OF THE HORMONES
Chemically, the hormones are of three basic types:
(1) Steroid hormones: These all have a chemical structure similar to that of
cholesterol and in most instances are derived from cholesterol itself. Different
steroid hormones are secreted by
(a) the adrenal cortex (cortisol and aldosterone),
(b) the ovaries (estrogen and progesterone), (c) the testes (testosterone), and (d) the
placenta (estrogen and progesterone),
(2) Derivatives of the amino acid tyrosine: Two groups of hormones are
derivatives of the amino acid tyrosine. The two metabolic thyroid hormones,
thyroxine and triiodothyromine, are iodinated forms of tyrosine derivatives. And
the two principal hormones of the adrenal medullae, epinephrine and
norepinephrine, are both catecholamines, also derived from tyrosine.
(3) Proteins or peptides: All the remaining important endocrine hormones are
either proteins, peptides, or immediate derivatives of these. The anterior pituitary
hormones are either proteins or large polypeptides; the posterior pituitary
hormones, antidiuretic hormone and oxytocin, are peptides containing only eight
amino acids. And insulin, glucagon, and parathormone are all large polypeptides.
HORMONE RECEPTORS AND THEIR ACTIVATION
The endocrine hormones almost never act directly on the intracellular machinery to
control the different cellular chemical reactions; instead, they almost invariably
first combine with hormone receptors on the surfaces of the cells or inside the
cells. The combination of hormone and receptor then usually initiates a cascade of
reactions in the cell.
Either all or almost all hormonal receptors are very large proteins, and each cell
usually has some 2000 to 10,000 receptors.
Also, each receptor is usually highly specific for a single hormone; this determines
the type of hormone that will act on a particular tissue. Obviously, the target
tissues that are affected by a hormone are those that contain its specific receptors.
The locations of the receptors for the different types of hormones are generally the
following:
(1) In the membrane. The membrane receptors are specific mostly to the protein,
peptide, and catecholamine (epinephrine and norepinephrine) hormones.
(2) In the cytoplasm. The receptors for the different steroid hormones are found
almost entirely in the cytoplasm.
(3) In the nucleus. The receptors for the metabolic thyroid hormones (thyroxine
and triiodothyronine) are found in the nucleus, believed to be located in direct
association with one or more of the chromosomes.
MECHANISMS OF HORMONAL ACTION
Activation of the Receptors. The receptors in their unbound state usually are
inactive, and the intracellular mechanisms that are associated with them are also
inactive. However, in a few instances the unbound receptors are in the active form,
and when bound with the hormone they become inhibited.
Activation of a receptor occurs in different ways for different types of receptors.
In general, the transmitter substance combines with the receptor and causes a
conformational change of the receptor molecule; this in turn alters the membrane
permeability to one or more ions, especially sodium, chloride, potassium, and
calcium ions. A few of the general endocrine hormones also function in this same
way – for instance, the effect of epinephrine and norepinephrine in changing the
membrane permeability in certain of their target tissues.
In addition to this occasional direct effect of hormone receptors to change cell
membrane permeability, there are also two very important general mechanisms by
which a large share of the hormones function: (1) by activating the cyclic AMP
system of the cells, which in turn activates multiple other intracellular functions; or
(2) by activating the genes of the cell, which cause the formation of intracellular
proteins that in turn initiate specific cellular functions. These two general
mechanisms are described as follows:
THE CYCLIC AMP MECHANISM FOR CONTROLLING CELL
FUNCTION – A "SECOND MESSENGER" FOR HORMONE MEDIATION
Many hormones exert their effects on cells by first causing the substance cyclic
3' ,5'-adenosine monophosphate (cyclic AMP) to be formed in the cell. Once
formed, the cyclic AMP causes the hormonal effects inside the cell. Thus, cyclic
AMP is an intracellular hormonal mediator. It is also frequently called a second
messenger for hormone mediation—the "first messenger" being the original
stimulating hormone.
The cyclic AMP mechanism has been shown to be a way in which all the
following hormones (and many more) can stimulate their target tissues:
1. Adrenocorticotropin
2. Thyroid-stimulating hormone
3. Luteinizing hormone
4. Follicle-stimulating hormone
5. Vasopressin
6. Parathyroid hormone
7. Glucagon
8. Catecholamines
9. Secretin
10. The hypothalamic releasing hormones.
The stimulating hormone first binds with a specific "receptor" for that hormone
on the membrane surface of the target cell. The specificity of the receptor
determines which hormone will affect the target cell. After binding with the
membrane receptor, the combination of hormone and receptor activates the protein
enzyme adenyl cyclase. This enzyme is also located in the membrane and is either
bound directly with the receptor protein or closely associated with it. However, a
large portion of the adenyl cyclase enzyme protrudes through the inner surface of
the membrane into the cytoplasm and, when activated, causes immediate
conversion of much of the cytoplasmic ATP into cyclic AMP.
Once cyclic AMP is formed inside the cell it activates still other enzymes. In
fact, it usually activates a cascade of enzymes. That is, a first enzyme is activated
and this activates another enzyme, which activates still a third, and so forth. The
importance of this mechanism is that only a few molecules of activated adenyl
cyclase in the cell membrane can cause many more molecules of the next enzyme
to be activated, which can cause still many times that many molecules of the third
enzyme to be activated, and so forth. In this way, even the slightest amount of
hormone acting on the cell surface can initiate a very powerful cascading
activating force for the entire cell.
The specific action that occurs in response to cyclic AMP in each type of target
cell depends upon the nature of the intracellular machinery, some cells having one
set of enzymes and other cells having other enzymes. Therefore, different functions
are elicited in different target cells— such functions as
(1) initiating synthesis of specific intracellular chemicals,
(2) causing muscle contraction or relaxation,
(3) initiating secretion by the cells,
(4) altering the cell permeability,
(5) and many other possible effects.
ACTION OF STEROID HORMONES ON THE GENES TO CAUSE
PROTEIN SYNTHESIS
A second major means by which hormones— specifically the steroid hormones
secreted by the adrenal cortex, the ovaries, and the testes—act is to cause synthesis
of proteins in the target cells; these proteins then function as enzymes or transport
proteins that in turn activate other functions of the cells.
The sequence of events in steroid function is the following:
1. The steroid hormone enters the cytoplasm of the cell, where it binds with a
specific receptor protein,
2. The combined receptor protein/hormone then diffuses into or is transported
into the nucleus.
3. The combination now activates the transcription process of specific genes to
form messenger RNA.
4. The messenger RNA diffuses into the cytoplasm where it promotes the
translation process at the ribosomes to form new proteins.
To give an example, aldosterone, one of the hormones secreted by the adrenal
cortex, enters the cytoplasm of renal tubular cells, which contain its specific
receptor protein. Therefore, in these cells the above sequence of events ensues.
After about 45 minutes, proteins begin to appear in the renal tubular cells that
promote sodium reabsorption from the tubules and potassium secretion into the
tubules. Thus, there is a characteristic delay in the beginning action of the steroid
hormone of 45 minutes and up to several hours or even days for full action, which
is in marked contrast to the almost instantaneous action of some of the peptide and
amino acid-derived hormones, such as vasopressin and norepinephrine.
CONTROL OF PITUITARY SECRETION BY THE HYPOTHALAMUS
Almost all secretion by the pituitary is controlled by either hormonal or nervous
signals from the hypothalamus. Indeed, when the pituitary gland is removed from
its normal position beneath the hypothalamus and transplanted to some other part
of the body, its rates of secretion of the different hormones (except for prolactin)
fall to low levels – in the case of some of the hormones, almost to zero.
Secretion from the posterior pituitary is controlled by nerve fibers originating in
the hypothalamus and terminating in the posterior pituitary. In contrast, secretion
by the anterior pituitary is controlled by hormones called hypothalamic releasing
and inhibitory hormones (or factors) secreted within the hypothalamus itself and
then conducted to the anterior pituitary through minute blood vessels called
hypothalamic-hypophysial portal vessels. In the anterior pituitary these releasing
and inhibitory hormones act on the glandular cells to control their secretion.
The hypothalamus receives signals from almost all possible sources in the
nervous system. Thus, when a person is exposed to pain, a portion of the pain
signal is transmitted into the hypothalamus. Likewise, when a person experiences
some powerful depressing or exciting thought, a portion of the signal is transmitted
into the hypothalamus. Olfactory stimuli denoting pleasant or unpleasant smells
transmit strong signal components directly and through the amygdaloid nuclei into
the hypothalamus. Even the concentrations of nutrients, electrolytes, water, and
various hormones in the blood excite or inhibit various portions of the
hypothalamus. Thus, the hypothalamus is a collecting center for information
concerned with the internal well-being of the body, and in turn much of this
information is used to control secretions of the many globally important pituitary
hormones.
THE HYPOTHALAMIC-HYPOPHYSIAL PORTAL SYSTEM
The anterior pituitary is a highly vascular gland with extensive capillary sinuses
among the glandular cells. Almost all the blood that enters these sinuses passes
first through a capillary bed in the tissue of the lower tip of the hypothalamus and
then through sma:ll hypothalamic-hypophysial portal vessels into the anterior
pituitary sinuses. Small blood vessels project into the substance of the median
eminence and then return to its surface, coalescing to form the hypothalamichypophysial portal vessels. These in turn pass downward along the pituitary stalk
to supply blood to the anterior pituitary sinuses.
Secretion of Hypothalamic Releasing and Inhibitory Hormones into the Median
Eminence. Special neurons in the hypothalamus synthesize and secrete hormones
called hypothalamic releasing and inhibitory hormones (or releasing and inhibitory
factors) that control the secretion of the anterior pituitary hormones. These neurons
originate in various parts of the hypothalamus and send their nerve fibers into the
median eminence and the tuber cinereum, the hypothalamic tissue that extends into
the pituitary stalk. The endings of these fibers are different from most endings in
the central nervous system in that their function is not to transmit signals from one
neuron to another but merely to secrete the hypothalamic releasing and inhibitory
hormones (factors) into the tissue fluids. These hormones are immediately
absorbed into the capillaries of the hypothalamic-hypophysial portal system and
carried directly to the sinuses of the anterior pituitary gland.
(To avoid confusion, the student needs to know the difference between a
"factor" and a "hormone." A substance that has the actions of a hormone but that
has not been purified and identified as a distinct chemical compound is called a
factor. Once it has been so identified it is thereafter known as a hormone instead of
simply a factor.)
Function of the Releasing and Inhibitory Hormones. The function of the
releasing and inhibitory hormones is to control the secretion of the anterior
pituitary hormones. For each type of anterior pituitary hormone there is usually a
corresponding hypothalamic releasing hormone; for some of the anterior pituitary
hormones there is also a corresponding hypothalamic inhibitory factor. For most of
the anterior pituitary hormones it is the releasing hormone that is important; but,
for prolactin, an inhibitory hormone probably exerts most control. The
hypothalamic releasing and inhibitory hormones (or factors) that are of major
importance are:
1. Thyroid-stimulating hormone releasing hormone (TRH), which causes
release of thyroid-stimulating hormone
2. Corticotropin -releasing (CRF), which causes release of adrenocorticotropin
3. Growth hormone releasing hormone (GHRH), which causes release of
growth hormone, and growth hormone inhibitory hormone (GHIH), which is the
same as the hormone somatostatin and which inhibits the release of growth
hormone
4. Luteinizing hormone releasing hormone (LRH), which causes release of both
luteinizing hormone and follicle-stimulating hormone – this hormone is also called
gonadotropin-releasing hormone (GnRH)
5. Prolactin inhibitory factor (PIF), which causes inhibition of prolactin
secretion
In addition to these more important hypothalamic hormones, still another
excites the secretion of prolactin, and several hypothalamic inhibitory hormones
inhibit some of the other anterior pituitary hormones. Each of the more important
hypothalamic hormones will be discussed in detail at the time that the specific
hormonal system controlled by them is presented in this and subsequent chapters.
Other Hypothalamic Substances That May Have Hormonal Effects. Multiple
other substances, especially many small peptides, are found in the neurons of the
hypothalamus. However, functions for these as hormones are only speculative.
Yet, because they are of research interest they are listed here: (1) substance P, (2)
neurotensin, (3) angiotensin II, (4) enkephalins, (5) endorphins, (6) uasoactive
inhibitory polypeptide, and (7) cholecystokinin-8. Many of these same substances
are also found in neurons elsewhere in the brain, suggesting that they may function
as neurotransmitters both in the hypothalamus and elsewhere. In addition, some of
them are in the neurons of the enteric nervous system of the gastrointestinal tract,
functioning there also as neurotransmitters possibly as hormones released into the
circulating blood from the nerve endings.
Key words and phrases: hypothalamus, hypophysis, epinephral glands,
adrnenaline, noradrenaline, somatotropin, thyrotropin, adrenocorticotropin,
lutropin, folitropin, antidiuretic hormone.
Theme 2
Thyroid Gland.
(1 and 2) Thyroxine and triidothyronine: increase the rates of chemical
reactions in almost all cells of the body, thus increasing the general level of body
metabolism.
(3) Calcitonin: promotes the deposition of calcium in the bones and thereby
decreases calcium concentration in the extracellular fluid.
Islets of Langerhans in the Pancreas.
(1) Insulin: promotes glucose entry into most cells of the body, in this way
controlling the rate of metabolism of most carbohydrates.
(2) Glucagon: increases the release of glucose from the liver into the
circulating body fluids.
Ovaries.
(1) Estrogens: stimulate the development of the female sex organs, the breasts,
and various secondary sexual characteristics.
(2) Progesterone: stimulates secretion of "uterine milk" by the uterine
endometrial glands; also helps promote development of the secretory apparatus of
the breasts.
Testes.
(1) Testosterone: stimulates growth of the male sex organs; also promotes the
development of male secondary sex characteristics.
Parathyroid Gland.
(1) Parathormone: controls the calcium ion concentration in the extracellular
fluid by controlling (a) absorption of calcium from the gut, (b) excretion of
calcium by the kidneys, and (c) release of calcium from the bones.
Placenta.
(1) Human chorionic gonadotropin: promotes growth of the corpus luteum
and secretion of estrogens and progesterone by the corpus luteum.
(2) Estrogens: promote growth of the mother's sex organs and of some of the
tissues of the fetus.
(3) Progesterone: probably promotes development of some of the fetal tissues
and organs; helps promote development of the secretory apparatus of the mother's
breasts.
(4) Human somatomammotropin: probably promotes growth of some fetal
tissues as well as aiding in the development of the mother's breasts.
The Thyroid Metabolic Hormones
The thyroid gland, which is located immediately below the larynx on either
side of and anterior to the trachea, secretes two significant hormones, thyroxine
and triiodothyronine, that have a profound effect on the metabolic rate of the body.
It also secretes calcitonin, an important hormone for calcium metabolism.
FUNCTIONS OF THE THYROID HORMONES IN THE TISSUES
The thyroid hormones have two major effects on the body: (1) an increase in
the overall metabolic rate, and (2) in children, stimulation of growth.
GENERAL INCREASE IN METABOLIC RATE
The thyroid hormones increase the metabolic activities of almost all tissues of
the body (with a few notable exceptions such as the brain, retina, spleen, testes,
and lungs). The basal metabolic rate can increase to as much as 60 to 100 per cent
above normal when large quantities of the hormones are secreted. The rate of
utilization of foods for energy is greatly accelerated. The rate of protein synthesis
is at times increased, while at the same time the rate of protein catabolism is also
increased. The growth rate of young persons is greatly accelerated. The mental
processes are excited, and the activity of many other endocrine glands is often
increased. Yet despite the fact that we know all these many changes in metabolism
under the influence of the thyroid hormones, the basic mechanism (or mechanisms)
by which the hormones function is much less well known.
EFFECT OF THYROID HORMONE ON GROWTH
Thyroid hormone has both general and specific effects on growth. For
instance, it has long been known that thyroid hormone is essential for the
metamorphic change of the tadpole into the frog. In the human being, the effect of
thyroid hormone on growth is manifest mainly in growing children. In those who
are hypothyroid, the rate of growth is greatly retarded. In those who are
hyperthyroid, excessive skeletal growth often occurs, causing the child to become
considerably taller than otherwise. However, the epiphyses close at an early age so
that the duration of growth, and the eventual height of the adult, may be shortened.
An important effect of thyroid hormone is to promote growth and
development of the brain during fetal life and for the first few years of postnatal
life. If the fetus does not secrete sufficient quantities of thyroid hormone, growth
and maturation of the brain both before birth and afterward are greatly retarded.
Without specific thyroid therapy within days or weeks after birth, the child will
remain mentally deficient throughout life.
REGULATION OF THYROID HORMONE SECRETION
To maintain normal levels of metabolic activity in the body, precisely the
right amount of thyroid hormone must be secreted all the time, and to provide this,
specific feedback mechanisms operate through the hypothalamus and anterior
pituitary gland to control the rate of thyroid secretion. These mechanisms can be
explained as follows:
Effects of Thyroid-Stimulating Hormone on Thyroid Secretion. Thyroidstimulating hormone (TSH), also known as thyrotropin, is an anterior pituitary
hormone, a glycoprotein with a molecular weight of about 28,000.
Hypothalamic Regulation of TSH Secretion by the Anterior Pituitary –
Thyrotropln-ReleasIng Hormone (TRH)
Electrical stimulation of multiple areas of the hypothalamus increases the
anterior pituitary secretion of TSH and correspondingly increases the activity of
the thyroid gland. This control of anterior pituitary secretion is exerted by a
hypothalamic hormone, thyrotropin-releasing hormone TRH), which is secreted by
nerve endings in the median eminence of the hypothalamus and then transported
from there to the anterior pituitary in the hypothalamic-hypophysial portal blood.
The precise nuclei of the hypothalamus that are responsible for causing secreting
of TRH in the median eminence are not known. However, injection of radioactive
antibodies that attach specifically to TRH have shown this hormone to be present
in many different hypothalamic loci, including the (1) dorsomedial nucleus, (2)
suprachiasmatic nucleus, (3) ventromedial nucleus, (4) anterior hypothalamus, (5)
preoptic area, and (6) paraventricular nucleus.
Insulin, Clucagon, and Diabetes Mellitus
The pancreas, in addition to its digestive functions, secretes two important
hormones, insulin and glucagon. The purpose of this chapter is to discuss the
functions of these hormones in regulating glucose, lipid, and protein metabolism,
as well as to discuss briefly the two diseases – diabetes mellitus and
hyperinsulinism—caused, respectively, by hyposecretion of insulin and excess
secretion of insulin.
INSULIN AND ITS METABOLIC EFFECTS
Insulin was first isolated from the pancreas in 1922 by Banting and Best, and
almost overnight the outlook for the severely diabetic patient changed from one of
rapid decline and death to that of a nearly normal person.
Historically, insulin has been associated with "blood sugar," and, true enough,
insulin does have profound effects on carbohydrate metabolism. Yet, it is mainly
abnormalities of fat metabolism, causing such conditions as acidosis and
arteriosclerosis, that are the usual causes of death of a diabetic patient. And, in
patients with prolonged diabetes, the inability to synthesize proteins leads to
wasting of the tissues as well as many cellular functional disorders. Therefore, it is
clear that insulin affects fat and protein metabolism almost as much as it does
carbohydrate metabolism.
EFFECT OF INSULIN ON CARBOHYDRATE METABOLISM
Immediately after a high carbohydrate meal, the glucose that is absorbed into
the blood causes rapid secretion of insulin, which we shall discuss in detail later in
the chapter. The insulin in turn causes rapid uptake, storage, and use of glucose by
almost all tissues of the body, but especially by the liver, muscles, and adipose
tissue. Therefore, let us discuss each of these.
Effect of Insulin on Promoting Liver Uptake, Storage, and Use of Glucose
One of the most important of all the effects of insulin is to cause most of the
glucose absorbed after a meal to be stored almost immediately in the liver in the
form of glycogen. Then, between meals, when food is not available and the blood
glucose concentration begins to fall, the liver glycogen is split back into glucose,
which is released back into the blood to keep the blood glucose concentration from
falling too low.
The mechanism by which insulin causes glucose uptake and storage in the
liver includes several almost simultaneous steps:
1. Insulin inhibits phosphorylase, the enzyme that causes liver glycogen to
split into glucose. This obviously prevents breakdown of the glycogen that is
already in the liver cells.
2. Insulin causes enhanced uptake of glucose from the blood by the liver cells.
It does this by increasing the activity of the enzyme glucokinase, which is the
enzyme that causes the initial phosphorylation of glucose after it diffuses into the
liver cells. Once phosphorylated, the glucose is trapped inside the liver cells,
because phosphorylated glucose cannot diffuse back through the cell membrane.
3. Insulin also increases the activities of the enzymes that promote glycogen
synthesis, including phosphofructokinase that causes the second stage in the
phosphorylation of the glucose molecule and glycogen synthetase that is
responsible for polymerization of the monosaccharide units to form the glycogen
molecules.
EFFECT Of INSULIN ON FAT METABOLISM
Though not quite as dramatic as the acute effects of insulin on carbohydrate
metabolism, insulin also affects fat metabolism in ways that, in the long run, are
perhaps equally as important. Especially dramatic is the long-term effect of insulin
lack in causing extreme atherosclerosis, often leading to heart attacks, cerebral
strokes, and other vascular accidents. But, first, let us discuss the acute effects of
insulin on fat metabolism.
Effect of Insulin on Protein Synthesis and Storage. During the few hours
following a meal when excess quantities of nutrients are available in the circulating
blood, not only carbohydrates and fats but proteins as well are stored in the tissues;
insulin is required for this to occur. The manner in which insulin causes protein
storage is not as well understood as the mechanisms for both glucose and fat
storage. Some of the facts known are:
1. Insulin causes active transport of many of the amino acids into the cells.
Among the amino acids most strongly transported are valine, leucine, isoleucine,
tyrosine, and phenylalanine. Thus, insulin shares with growth hormone the
capability of increasing the uptake of amino acids into cells. However, the amino
acids affected are not necessarily the same ones.
2. Insulin has a direct effect on the ribosomes to increase the translation of
messenger RNA, thus forming new proteins. In some unexplained way, insulin
"turns on" the ribosomal machinery. In the absence of insulin the ribosomes simply
stop working, almost as if insulin operates an "on-off" mechanism.
3. Over a longer period of time insulin also increases the rate of transcription
of DNA in the cell nuclei, thus forming increased quantities of RNA. Eventually, it
also increases the rate of formation of new DNA and thus promotes reproduction
of cells. All these effects promote still more protein synthesis.
4. Insulin also inhibits the catabolism ofproteins, thus decreasing the rate of
amino acid release from the cells, especially from the muscle cells. Presumably
this results from some ability of the insulin to diminish the normal degradation of
proteins by the cellular lysosomes.
5. In the liver, insulin depresses the rate of gluconeogenesis. It does this by
decreasing the activity of the enzymes that promote gluconeogenesis. Since the
substrates most used for synthesis of glucose by the process of gluconeogenesis are
the plasma amino acids, this suppression of gluconeogenesis conserves the amino
acids in the protein stores of the body.
CONTROL OF INSULIN SECRETION
Formerly, it was believed that insulin secretion is controlled almost entirely
by the blood glucose concentration. However, as more has been learned about the
metabolic functions of insulin for protein and fat metabolism, it has been learned
that blood amino acids and other factors also play important roles in controlling
insulin secretion.
Stimulation of Insulin Secretion by Blood Glucose. At the normal fasting
level of blood glucose of 80 to 90 mg/dl, the rate of insulin secretion is minimal –
in the order of 25 ng/min/kg (600 (xUnits/min/kg) of body weight. If the blood
glucose concentration is suddenly increased to a level two to three times normal
and is kept at this high level thereafter, insulin secretion increases markedly in two
stages.
1. Insulin secretion increases almost tenfold within 3 to 5 minutes after acute
elevation of the blood glucose; this results from immediate dump ing of preformed
insulin from the beta cells of the islets of Langerhans. However, this initial high
rate of secretion is not maintained; instead, it decreases about halfway back toward
normal in another 5 to 10 minutes.
2. After about 15 minutes, insulin secretion rises a second time, reaching a
new plateau in 2 to 3 hours, this time usually at a rate of secretion even greater
than that in the initial phase. This secretion results both from additional release of
preformed insulin and from activation of some enzyme system that synthesizes and
releases new insulin from the cells.
Relationship Between Blood Glucose Concentration and Insulin Secretion
Rate. As the concentration of blood glucose rises above 100 mg/dl of blood, the
rate of insulin secretion rises rapidly, reaching a peak some 10 to 30 times the
basal level at blood glucose concentrations between 400 and 600 mg/dl. Thus, the
increase in insulin secretion under a glucose stimulus is dramatic both in its
rapidity and in the tremendous level of secretion achieved.
Key words and phrases: thyroid glands and hormones, pancreas
(insulin,glucagons),sex glands, sex hormones (estrogen, testosteron), thymus,
tissue hormones (prostaglandines).
Theme 3
1. Neural regulation
a) Development of somatic nerves system (Spinal cord develops faster than
other parts of nervous system. In the later period of embrio, columna vertebralis
grows faster then spinal cord. In newborns, the length of spinal cord is 14-16
santimetres, to 10 years it double. The main tracts of spinal cord have myelin
sheaths. At the moment of birth of baby medulla oblongata is rather developed, the
bigger part of nuclei thalamici is developed, the striopalidal system is developed
rather good. Cortex of hemisphere cerebri has the same construction as adults one.
However, during the first months of life the development of cortex goes in very
fast speed. The development of the nuclei of hypothalamus is finished during the
teenagers period. Frontal parts of the cortex mature the most later.)
b) Reflectory activity of fetus (After one week of fetus life begins to form
reflector arc of spinal cord. When it will be the stimulation of fetus, it will be quick
movement of arm, trunk, or generelazing moving reaction. That is why it presents
irradiation in central nervous system, analysis of irritation. In the 9-10 weeks of
fetus life present moving reaction in the case of stimulation of proprioreceptors. In
11,5 week are present seizing reactions, in 14 week beginning rythmical movement
of breathing muscles. The tone of flexor muscles is increase.)
c) Development of somatic reflexes in children (In newborns tone of flexor
muscles are more then tone of extensor muscles. In 1-2 months the tone of extensor
muscles are more. In 3-5 months the tone of flexor and extensor muscles are
balansed. These depend from the development of corpus striatum and pyramidal
system. Oriental reflexes, autonomic vision, seing are inborn. The last reflex
present from a middle of 3 month to 3,5 month. We can understand that child may
see. In newborn present moving reflectory reaction, which are present in the case
of stimulation of vestibular apparatus, present reflex of snatch to 3-6 month. To 5
years present reflex of Babinsky – straightening out the toes in the case of
stimulation of outer part of sole. In newborns are present stretch reflexes (they are
increase from 6 to 12 month). In newborns are present suck reflex (to the end of 1
yae). In newborns are present uncoordinating moving of arms, legs, head. In 1-1,5
month of newborn life may support the head in vertical position. From 6-7 month
the infant may seat, from 10 month it may seat with different position. It may
standing in the 10 month independently. Near one year baby may stand up and
going.)
d) Peculiarities of electroencephalogram in children (Subcortical structures may
mature earlier than cortex. Slowly activity of electroencephalogram may
registrated in newborns. The alpha-rythm may registrated from 3 month, but only
from 6 years it become main. From 6-8 years present teta-rythm (cortex-subcortex
connection). In 10-12 years alpha-rethm is the same as in adult. From 12 to 15
years decrease the frequency of alpha-rethm.)
e) Changes of nervous system in old persons (In old person the weight of brain
decrease, the gyrus become thin, the sulcus is broadened and deepened, ventricles
of brain become broadened. Quantity of neurons decrease and glial cells increase.
In old person increase the quantity of lipophyscin (product of oxidation of
unsaturated fatty acids). Decrease the excitability, the speed of transmition of
excitement, synaptic transmition, quantity of receptors, activity of Na-K-ATPase,
permeability of membrane cannels, inhibitory processes. On electroencephalogram
alpha-rythm is slow, increase teta and delta-rythms.)
f) Peculiarities of autonomic regulation (On early stages of postnatal period of
regulation of inner organs take place sympathetic nervous system. Tone of
parasympathetic nervous system is low, and include in providing of some reflex
reaction from 2 to 3 month. The influence of autonomic system on different organs
more strong on digestive tract (parasympathetic part), hart (sympathetic part) in
newborns. In newborns ganglion transmition act by help of adrenergic system. In
old persons influence of autonomic system decrease.)
2. Hormonal regulation
a) Functioning of pituitary, adrenal, sex and thyroid glands (Pituitary glands of
newborns has weight 0,1-0,15 gram and increase to 10 years to 0,3 gram, to 16
year is 0,7 gram. In old person it decrease. In 16 week of fetus life produced
gonadotropins which need for differenciation of sex organs. They increase in sex
micturation period. Growth hormon regulate growth from 2 to 18 years (lenth of
bones). Quantity of antidiuretic hormon in newborns less. The cortex of adrenal
glands is more develope than medulla in newborns. To 6-8 years sex hormones do
not produced. Male sex glands begin to produce the hormons from 3 month of
embrion life; it stopped to the end of embrion life. They begin to produce in the
period of sex micturation in female, and second time produce in the period of sex
micturation in male. Maximal production of hormones produce of male in 25-35
years, then they slowly decrease; in female sex hormones produced to the period of
the end of menstruation. Thymus increase to the age 3-5 years, more intensivity
grows are in 11-15 years. After 30 years it decrease in size, but increase production
of glucocorticoids, sex hormones. Secretion of thiroid hormones are more in
children, then in adult (maximal production in the first week of newborn life and in
12-15 years.)
b) Sex development (This is the process of forming reproductive function of
organism. In female it stopped to 16-18 years, in male – to 18-20 years. There are 3
stages of sex development: prepubertate (increase the size of testis in male,
increase the size of mammaliar glands in female), pubertate (to the first pollution
in male and first menstruation in female), postpubertate (to the junior acne and
growth of hears on face in male).)
c) Climacteric period in female (Climacteric period is the physiological period
of transmition from sex development to stopped the generative function.
Climacteric period in female is from 45 to 60 years and characterizated by process
of slowly decrease menstruation, hormonal function of ovarium on the fone of
common age change of organism. There are two period of climacteric period. First
fase of climacteric period – the fase of climacteric disfanction of ovarium or
premenopausa. This period is in 45 years. The menstrual cycle from 2-fases
become one-fases. Second period of climacteric period – postmenopausa –
characterizated by whole absent of functioning of yellow body, decrease of
production of estrogens and stopping the menstrual function.)
d) Climacteric period in male (Climacteric period in male determined by age
involutive processes, which are present in sex glands and are from 50 to 60 years.
The quantity of testosterons and androgens decrease and honadotropic hormones
are increase. These process may be with clinic picture of climacteric period, but in
the biggest part of male the climacteric manifistations are absent.)
Key words and phrases: climacteric period, embrio, striopalidal system,
prepubertate, pubertate, postpubertate, premenopausa, climacteric manifistations
Students must know:
Theme 1
1. Structuro-functional characteristic of endocrine system
a) Classification of endocrine glands
b) Classification of hormones
c) Mechanism of hormone action
d) Types of hormonal effects
e) Ways of regulation of endocrine glands
f) Methods of studying of endocrine glands
2. Physiology of hypothalamo-pituitary system
a) Morpho-functional peculiarities
b) Growth hormone action
c) Role of gonadotropic hormones
d) Influences of thyreotropic hormone
e) Adrenocorticotropic hormone action
f) Melanocytesstimulated hormone action
g) Role of neurohypophyses hormones
3. Physiology of adrenal glands
a) Morpho-functional peculiarities
b) Mineralocorticoids action
c) Effects of glucocorticoids
d) Role of sex hormones
e) Adrenal medulla hormone action
4. Common adaptative syndrome, its stages
Theme 2
1. Physiology of thyroid and parathyroid glands
a) Synthesis of iodide hormones
b) Action of iodide hormones
c) Physiologic effect of thyreocalciotonine
d) Action of parathyroid hormone
2. Endocrine funcion of pancreas
a) Anatomic physiology
b) Action of insuline
c) Influences of glucagon
d) Regulation of islands secretion
3. Physiology of sex glands
a) Effects of male and female sex hormones
b) Regulation of action of sex glands
c) Female menstrual cicle
d) Endocrine function of placenta
4. Meaning of thymus and tissue' hormones
Theme 3
1. Main type of nutrients transport
2. Absorption in the mouth cavity and stomach
Students should be able to:
1. To analyze action of hormones
2. To analyze absorptive processes
3. To value the absorption processes in digestive system
Tests and Assignments for Self-assessment
Multiple Choice.
Choose the correct answer/statement:
Theme 1
1. In experiment student irritant the middle part of adrenal cortex. It was increasing
and than decreasing of glucocorticoids secretion. Which hormone of pituitary
gland takes part in this case?
a) Growth hormone; b) Thyroid hormone; c) Gonadotropine; d) Aldosterone;
e) Adrenocorticotropin.
Real-life situation to be solved:
1. In experiment student irritant the middle part of adrenal cortex. It was increasing
and than decreasing of glucocorticoids secretion. What do you think about this?
Answers for the Self-control
1. e;
1. It was according to action of hypothalamus (secretion of liberins and statins) –
pituipary gland (secretion of adrenocorticotropin) – adrenal gland action.
Theme 2
1. Student investigated action of hormones on adipose tissue. Which hormones he
can take?
a) growth hormone, esrtogens; b) tissue, thyroid hormones; c) insulin,
thymothin; d) insuline, glucagon; e) liberins, melatonine
Real-life situations to be solved:
1. Person J., 23 years old eat cake of 150 gramms. What is about his glucose blood
level?
Answers for the Self-Control
1. d
1 real-life situation – It normal, because of insulin action.
Theme 3
1. Which hormones are determine the growth of organism?
a) androgens, esrtogens; b) growth hormone, thyroid hormones; c) insulin,
adrenocorticotropic hormone; d) glucocorticoids, adrenalin; e) liberins, melatonine
Real-life situations to be solved:
1. Child F., 3 years old has battered knees. They are battered when he was run.
Why they are battered?
Answers for the Self-Control
1. b
1 real-life situation – To 5 years present positive reflex of Babinsky – straightening
out the toes in the case of stimulation of outer part of sole. That is why the knee are
battered.
References:
1. Review of Medical Physiology // W.F.Ganong. – Twentieth edition, 2001. – P.
233-242, 307- 368, 383- 438.
2. Textbook of Medical Physiology // A.C.Guyton, J.E.Hall. – Tenth edition, 2002.
– P. 684, 706, 836-844, 846-856, 858-865, 869-880. 884-894, 899-910, 916-926,
929-939, 948-950. 958-959, 965-966.
Затверджено на методичній нараді кафедри
протокол №
Затверджено на цикловій методичній комісії з дисциплін фізіологічного і
морфологічного профілів
протокол №
Adopted at the Cyclic Methological Committee of physiological and morphological
departments
Minutes No
Adopted at the Cyclic English Committee