Question

Study the following events related to Na and K voltage-gated channels and find the correct combination:

S.No	Channel	Gate	Resting Phase	Depolarised	Hyperpolarized	Repolarisation	Speed of response
A	Na	Activation gate	Closed	Open	Open	Closed	Fast
B	Na	Inactivation gate	Open	Open	Closed	Slow
C	K	Activation gate	Closed	Closed	Open	Open	Slow

• A. A
• B. B
• C. C
• D. Both A and C

Answer 1

The correct option is A A

The type of gate or sodium channels in the neurons is of activaetd type. When the neuonal membrane is at resting phase, the sodium channels are closed. When there is impulse generation, there is depolarisation of the membrane which results in the opening of the sodium channels. The channels are in open state, when the neuron is in hyperpolarised state. The gates close when the membrane comes back to resting phase after repolarisation. The speed of response is very fast as there is flow of three sodium ions through the channel.

Thus, the correct answer is option A.