7 The action potential does not reverse direction on its own

7. The action potential does not reverse direction on its own because

a) The voltage-gated K+ channels are in their open state.

b) The voltage-gated Na+ channels cannot transition directly from inactive to open states.

c) The voltage-gated Na+ channels are in their inactivated states.

d) The delayed rectifier K+ channels cannot transition directly from inactive to open states.

Solution

Option b) The voltage-gated Na+ channels cannot transition directly from inactive to open states.

Action potential is followed by refractory period. In the refractory period sodium channels enter an \"inactivated\" state, in which they cannot be made to open regardless of the membrane potentia. This is responsible for the unidirectional flow of action potential.