Why does an action potential move in only one direction down the axon? Drag the terms on the left to the appropriate blanks on the right to complete the sentences. The refractory period – once a region of the membrane has experienced an action potential, it becomes unresponsive and of undergoing another action potential. It can be divided into two periods known as the and refractory periods. refractory periods are due to the inactivation of sodium channels. refractory periods are those where a new action potential is possible but difficult to incapable initiate.