IV. Match words in A with words in B to form word combinations. Make up sentences with them.

V. Answer the following questions. Use all information given before:

1. Why are voltage-gated ion channels called so?

2. What the function of a sodium-potassium pump is?

3. What does the membrane permeability of a nerve fibre depend on?

4. What does an ion channel consist of?

5. What does the all-or-none law mean?

VI. Translate into English using all the active possible:

1. Внутреннее пространство нейрона заряжено отрицательно относительно внешнего в связи с неравномерным распределением заряженных ионов.

2. Величина потенциала действия не зависит от раздражителя.

3. Животные могут быстро реагировать на изменения в окружающей среде в связи со способностью нервных волокон быстро передавать информацию.

4. Нервный импульс – это информация, которая передаётся в форме электрических сигналов.

5. Возникновение нервного импульса связано с достаточно сильным раздражителем.

VII. Find English equivalents to the following word combinations and make up sentences with them:

VIII. Read and translate the short text without any dictionary

Fact of life:

Puffer fish produce a highly potent neurotoxin called tetrodotoxin. This selectively blocks the entry of sodium ions into nerve and muscle cells during an action potential, preventing the generation of nerve impulses and muscle contractions.

IX. State whether the voltage-gated potassium ion channels and the voltage-gated sodium ion channels in a neurone membrane are open or closed:

a) during the resting phase

b) during the depolarisation phase of the action potential

c) in the repolarisation phase

d) during the undershoot.

X. Suggest why depolarisation is not a good word for describing what happens during the transmission of an action potential.

XI. Explain how resting potential and action potential are connected with each other.

UNIT VI. EVOLUTION