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

The Na+/K+ ATPase restores the ion gradients across the plasma membrane of an axon after an action potential by actively transporting Na+ out of and K+ into the neuron. Option d.

Step-by-step explanation:

The activity that restores the ion gradients across the plasma membrane of an axon after an action potential is Pumping by the Na+/K+ ATPase option d. After an action potential, the resting state of the membrane potential, which is negatively charged inside relative to the outside, needs to be re-established. The Na+/K+ pump, which is an ATP-dependent mechanism, actively transports Na+ ions out of the neuron and K+ ions into the neuron, against their concentration gradients. This action restores the original ion distribution, ensuring that the neuron is ready for the next action potential. Voltage-gated Na+ and K+ channels play a role during the action potential itself, but it is the Na+/K+ ATPase that restores the ion balance following an action potential.