Question

What happens to the resting membrane potential of -70 mV when channels, that permit both sodium and potassium to move through, open ______.

A) depolarization
B) hyperpolarization
C) membrane stabilization
D) returns to -70 mV
E) repolarization

Answer 1

The resting membrane potential undergoes depolarization when Na+/K+ channels open, and subsequently, repolarization and a brief hyperpolarization as K+ ions exit the cell.

Step-by-step explanation:

When channels that permit both sodium (Na+) and potassium (K+) to move through open, the resting membrane potential of -70 mV experiences depolarization. During depolarization, the influx of Na+ ions into the cell makes the inside less negative and moves the membrane potential toward zero, causing the action potential to start.

When K+ channels then open, K+ ions exit the cell, returning the membrane potential toward the resting state in a process called repolarization. However, because K+ channels are slightly delayed in closing, there is a brief period of hyperpolarization, where the membrane potential becomes even more negative than the resting potential.