An Action Potential Travels in Only One Direction, Because

Question

An action potential travels in only one direction, because
A)the nodes of Ranvier are open only at the site of the action potential.
B)only the sodium channels "downstream" are open.
C)only the sodium channels at the site of the action potential remain open.
D)sodium ions can move only between the nodes of Ranvier.

Accepted Answer

During an action potential, sodium channels downstream (in the direction the action potential is moving) open in response to the depolarization wave, while those upstream (where the action potential has already passed) are in a refractory state and cannot immediately reopen. This ensures unidirectional propagation of the action potential.