Materials for auditory self-work. List of study practical tasks necessary to perform at the practical class.

List of study practical tasks necessary to perform at the practical class.

Materials and methods: istruments preparation set, metronom, stand, acids set (sulfuric acid 0,1%, 0,3%, 0,5%, 1,0% solutions), Ringer’s solution; glass, threads, novocain solution.

Investigation object: frog.

Task 1. Receptive field definition.

Every reflex has its own reflex field, i.e. body locus at irritation of which this reflex occurs. Response answer character at reflex field irritation depends not only on its localization on body surface but also on irritation force and duration.

Frog’s brain must be removed. After that you receive spinal frog’s preparation it’s necessary to wait 2-3 minutes for spinal shock phenomena disappearance. Then the investigators must hang the frog by his inferior jaw on the hook fixated in a stand. They wash filter paper piece in 0,1% sulfuric acid solution and put it on inferior leg tibia external skin surface. To observe flexory reaction of corresponding leg. To wash the leg from acid by means of leg’s plunging into water. To realize the irritation of the same leg with 0,3%, then with 0,5% of acid solutions. To choose those concentration at which one can see maximal flexory reflex. Paper with sulfuric acid of this concentration put on lateral abdomen surface. After some minutes you can observe defensive reflex: frog takes the paper off with the nearest leg. To put the paper to the external surface of anterior leg, on the abdomen near to the thoracic part, between superior and inferior legs. You must registrate answer reaction every time. The intervals between irritations must be at least 2-3 min. After each irritation you should put the frog to the glass with water and wash the animal from acid residues.

In second experiment you should put your attention to the correlation of reflex time to stimulus force (students must perform the experiments with all solutions (time must be fixed with metronom or watch with second pointer).

Task 2. Reflex arc analysis.

To prepare spinal frog and to hang it with inferior jaw on a stand. To put one of her legs in 0,5% of sulfuric acid.

Convince in reflex existence. To perform round skin incision below knee jerk and to release the leg from its skin. To irritate this leg tibia again. To observe the reaction.

To cut other posterior (inferior) leg hip skin of the same frog and to prepare sciatic nerve over the distance of 1,5-2,0 cm. To bring the thread under the nerve but not to tie it. To call flexion reflex by means of taking this leg fingers ends into acid. Then to tighten the nerve carefully by the thread and put the cotton wool washing into novocain solution under it for excitement transduction blocking into sciatic nerve fibers. To check the reflex existence.

To check the reflexes existence on superior legs.

To destroy the spine and to observe all reflexes disappearance.

On the base of investigations performed make the conclusion about reflex arc structure. Designate its links.

Task 3. Gustatory receptors functional mobility determining

(before and after eating).

To be convinced of eating leading to demobilization i.e. actively functioning gustatory receptors number decreasing.

The work must be performed on an empty stomach or at least after 3-4 hours after eating. The experienced person tongue must be dried with filter paper. Gustatory stimulus (sugar solution: 8 grams of sugar for 20 ml of dist water) must be taken on separate tongue fungiform papillas with pipette. 4 papillas becomes differentiated at this that give sweet taste sensation. It is one probe. Students must perform 5 probes with intervals 1-2 minutes between them. One must rinse mouth out after every probe. You should investigate the same papillas. The gustatory sensation appearance is marked in protocol with sign “+”, the disappearance- “-“. You should count positive answers common number and express mobilization level in per cents. The investigations must be repeated after eating (sweet tea glass with white bread).

5. Literature recommended:

1. Lecture course.

2. Mistchenko V.P., Tkachenko E.V. Methodical instructions for dental students (short lecture course).-Poltava, 2005.-P. 24-25.

3. Mistchenko V.P., Tkachenko E.V. Methodical instructions for medical students (short lecture course).-Poltava, 2005.-P.11-12.

4. Mistchenko V.P., Tkachenko E.V. Methodical instructions on Normal Physiology on practical classes for dental and medical students.-Poltava, 2005.-P.26-34.

5.Ganong W.F. Review of Medical Physiology.-21st ed.-2003.-Section II.

6. Kapit W., Macey R.I., Meisami E. The Physiology Colouring Book: Harpers Collins Publishers, 1987.-P. 17, 83-86.

7. Bullock J., Boyle III J., Wang M.B. Physiology.-1991.- P.

8. Guyton – Ganong – Chatterjee. Concise Physiology /Ed. By Dr Raja Shahzad Gull: M.B.B.S., F.C.P.S., King Edward Medical College.-Lahore, 1998 (1st Edition).-P. 261-263..

9. Guyton A.C. Textbook of Medical Physiology.-NY, 1992.-P. 572-577.


6.Materials for self-control:

A. Control questions.

1. The term “reflex”.

2. Reflex receptor zone.

3. Reflex reflectory arc and its structure.

4. Reflex time.

5. Reflexes classification.

6. Reflectory arcs types.

7. Receptors distingushing features.

8. Receptor and generator potential.

9. Receptors classification.

Excitement processes investigation in CNS. Inhibition processes investigation in CNS.

The topic studied actuality.

Synapse is nervous system morphological unit while nervous center is a functional one.

Pharmacological agents allow influence on central inhibition process. Topic studied is important in clinical practice: it is possible well-singlemindedly and separately influence on corresponding nervous centers which is connected with these chemicals structure because they can coincide nervous centers corresponding mediators. Excitement developmental regularities knowledge, excitement afteraction give opportunity to understand memory, study process, striated and non-striated muscular fibers tone as well as the one of blood vessels walls and so on.

2.Study aims:

To know: information conductance mechanisms in central synapses, neuromediators and neuromodulators role; excitement development and summation mechanisms and their role in CNS integrative function; excitement conductance peculiarities through central synapses; different inhibition types developmental mechanisms and these processes role in CNS integrative function.

To be able to: draw schematically excitement conductance mechanisms through central synapse as well mechanisms of EPSP temporary and spatial summation; to draw schematically pre- and postsynaptic inhibiting as well as recurrent inhibiting neuronal mechanisms.


3. Pre-auditory self-work materials.

3.1.Basic knowledge, skills, experiences, necessary for study the topic:

Subject To know To be able to
Medical biophysics Nervous impulse occurrence biophysical mechanisms explanation. Manage the skills of work on electrical and medical devices
Histology Neurons structure and functions; synapses and nervous centers structure Draw chemical synapses structure
Biochemistry Nervous tissue metabolism distinguishing features  
Neurology Nervous centers features and their possible disorders, representation about inhibition types, their significance and possible disorders.  


Topic content.


Organism reflectory activity is defined by general features of nervous centres in more extent. In narrow context, nervous centre is synapse as itself and in wider aspect it is neurons complex located at different floors of CNS (this term is not anatomical, but physiological one). So, nervous center is multi-leveled structure. Main function of any nervous center is definite reflectory acts performance or managing one of organism functions.

Principle of dynamic functions localization - functional nervous centre may be localized into different anatomical (morphological) structure. For instance, respiratory center:

– medulla oblongata – working part;

– diaphragmal nerves center (C2-C4 spine segments);

– hypothalamus – respiration changing during emotional reactions (for instance, breathing acceleration at lovely person touching, kissing et al.);

– cortex – respiration adaptation to separate conditions (in singers, in highlands, in sea depth and so on).

Nervous centres hierarchy – separate sides of one organism function are managed by nervous centres localized at different levels of nervous system.


Nervous centres common featuresare the following:

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