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 LvivUniversity with the medical faculty. In 1805 was opened the CharkivUniversity 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 KievUniversity. 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 OdessaUniversity. 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. Thisresting 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. Thesodium-potassiumpump 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 assodium-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 thelatent 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 thefiring 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 thespike potential of the axon, and the slower fall at the end of the process is theafter-depolarization. After reaching the previous resting level, the tracing overshoots slightly in the hyperpolarizing direction to form the small but prolongedafter-hyperpolarization. The after-depolarization is sometimes called thenegative 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 theaction 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 ademarcation 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. Thisrefractory period is divided into anabsolute refractory period,corresponding to the period from the time the firing level is reached until repolarization is about one-third complete; and arelative 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 after-hyperpolarization 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: