Добавил:
Upload Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:
part 1.doc
Скачиваний:
5
Добавлен:
01.07.2025
Размер:
5 Мб
Скачать
☆

Task 3. Nerve and muscle excitability measurement.

The investigation is performed on the preparation “ sciatic nerve-legs muscles”. The investigator put the preparation on the plate. The scientist puts sciatic nerve to the electrods. Then he slowly increases the voltage till the level at which the muscle will have minimal answer. The founded minimal irritation force is called the irritation threshold.

Then one should determine the muscle irritation threshold at its direct irritation by electrical current. For this gaim the investigator brings up the electrods to one of tibia muscles. Then he finds minimal irritation force causing muscular contraction.

Compare irritation and excitability threshold at direct muscular irritation and nerve irritation (indirect irritation). Make the final conclusion.

Task 4. Muscles contractions dependence on single irritations force.

The observations are performed on nerve-muscular preparation (gastrocnemius muscle and femur bone residue). The preparation are fixed in myograph and the electrods are brought up to the muscle. Find the threshold level. To perform this muscular contraction registration on kymograph. The investigator must write voltmeter numerals under the myogram. To continue the voltage increasing and myogram registration on kymograph. Then one must find the irritation level at which further altidude rising up is absent, i.e. the muscular contraction becomes maximal. These are so-called optimum irritation conditions.

After that one should increase quickly current force and determine the contraction force diminishing. The phenomenon observed is called force pessimum. The curves received must be glued into students’ copy-books.

The students must make the conclusion about dependence between irritation level and muscular contraction force. Explain the phenomena of force pessimum and optimum.

Task 5. Draw and analize the curve “force-time”.

To mark “rheobase”, “useful time”, “chronaxy” on your graphic. Make the conclusions.

  1. Literature recommended:

1. Lecture course.

2. Mistchenko V.P., Tkachenko E.V. Methodical instructions for dental students (short lecture course).-Poltava, 2005.-P.3-6.

3. Mistchenko V.P., Tkachenko E.V. Methodical instructions for medical students (short lecture course).-Poltava, 2005.-P. 3-6.

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

5. Bullock J., Boyle III J., Wang M.B. Physiology.-1991. P. 18-35.

  1. Materials for self-control: Control questions:

1.Irritability and irritation as they are.

2. Stimuli, definition and classification.

3. Excitability.

4. Call excitable tissues.

5. Law “everything or nothing”.

6. Muscular contraction force dependence on irritation force.

7. Stimulus threshold force dependence on its duration.

8. Excitability measures.

9. Lability as one of the excitable tissues features.

10. Excitability changes in course of excitement.

Content module 2: “excitable tissues physiology” lesson 2 Nervous and muscular fibers resting potential and action potential.

Соседние файлы в предмете [НЕСОРТИРОВАННОЕ]