Question

Which of the following activities restores the ion gradients across the plasma membrane of an axon after an action potential has occurred?

A. The opening of voltage-gated Na+ channels.
B. The opening of voltage-gated K+ channels.
C. The activity of K+ leak channels.
D. Pumping by the Na+/K+ ATPase.

Answer 1

Pumping by the Na+/K+ ATPase restores the ion gradients across the plasma membrane of an axon after an action potential.

Step-by-step explanation:

The activity that restores the ion gradients across the plasma membrane of an axon after an action potential has occurred is pumping by the Na+/K+ ATPase. During an action potential, voltage-gated Na+ channels open, causing depolarization of the membrane. However, after depolarization, the Na+/K+ ATPase pump actively transports molecules of sodium (Na+) out of the cell and molecules of potassium (K+) into the cell, restoring the resting potential of the membrane.