Which of the following does NOT describe conditions that occur during an action potential?

A) The Na+/K + pump reestablishes resting concentration gradients.

B) After initial depolarization, K + now has both an electrical and a chemical gradient drawing it out of the cell.

C) Na + enters the cell through voltage-gated channels, causing a reversal of the resting membrane potential.

D) Na + is used to repolarize the membrane.

D) Na + is used to repolarize the membrane.

Explanation:

Option D is wrong choice because it is K + which is used to repolarize the membrane not Na+.

As soon as membrane gets depolarized because of influx of Na + due to opening of voltage gated Na + channels simultaneous opening of voltage gated K + channels and closing of Na + voltage gated channels takes place. As a result of which K + moves out of the cell leading to drawing of electrochemical gradient out of the cell.

In order to achieve resting membrane potential, more Na + must be out of the cell and more K + must be inside the cell. There are many leaky channels on neurons from which Na + has tendency to leak into the cell while K + has the tendency to leak outside of the cell. So Na+/K + pump which is located on the membrane of neuron keeps pushing Na + outside of the cell and K + inside the cell so as to maintain resting membrane potential which is - 70 mV.