The positive feedback loop that is involved in the generation of an action potential is terminated by the .....

SYNAPTIC PHYSIOLOGY

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Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]

The positive feedback loop that is involved in the generation of an action potential is terminated by the ____

A	Opening of activation gates on sodium channels
B	Closure of activation gates on sodium channels
C	Opening of inactivation gates on sodium channels
D	Closure of inactivation gates on sodium channels

Explanation:

Detailed explanation-1: -The generation and propagation of the action potential requires sodium influx via voltage-dependent sodium channels that drives the upstroke of the action potential. This positive feedback cycle is terminated by sodium channel inactivation that shuts down the channel at depolarized membrane potentials.

Detailed explanation-2: -The fast-inactivating voltage-gated sodium channel is responsible for the positive feedback loop. These channels are more likely to open when the cell is depolarized, and their effect is to depolarize the cell by allowing sodium to flow down its electrochemical potential^, i.e. into the cell.

Detailed explanation-3: -Voltage-gated Na+ channels have two gates: an activation gate and an inactivation gate. The activation gate opens quickly when the membrane is depolarized, and allows Na+ to enter. However, the same change in membrane potential also causes the inactivation gate to close.

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