The return of a neuron's interior to a relative negative voltage immediately following the peak of the action potential is due to primarily to movement of
A)Na +.
B)Ca ++.
C)K +.
D)Cl -.

Question

Quizplus · Accepted Answer

The return of a neuron's interior to a relative negative voltage immediately following the peak of the action potential is due to primarily to movement of K+. During an action potential, there is an influx of positively charged ions (usually Na+) which causes the membrane potential to become more positive. However, K+ channels then open and K+ ions rush out of the cell, causing the membrane potential to become more negative again. The movement of Ca++ ions is involved in triggering neurotransmitter release, but does not play a significant role in the repolarization of the membrane potential. Cl- ions also play a role in maintaining the resting membrane potential by contributing to its negativity, but do not play a significant role in the repolarization phase of the action potential.

The Return of a Neuron's Interior to a Relative Negative