A refractory period after an action potential has past will allow the impulse to go backwards.
A refractory period after an action potential has past will not allow the impulse to go backwards.

Question

Quizplus · Accepted Answer

During refractory period, the voltage-gated sodium channels are inactivated and cannot reopen until the membrane potential returns to its resting state. This prevents the impulse from going backwards and ensures that the action potential moves in only one direction.

A Refractory Period After an Action Potential Has Past Will