Question

What process is responsible for the change in membrane potential that occurs between point 3 and point 4?

1) Movement of Na⁺ into the cell
2) Movement of Na⁺ out of the cell
3) Movement of K⁺ into the cell
4) Movement of K⁺ out of the cell
5) Activation of the Na⁺-K⁺ pump
6) Inhibition of the Na⁺-K⁺ pump

Answer 1

The movement of K+ out of the cell is responsible for the change in membrane potential between point 3 and point 4 of an action potential.

Step-by-step explanation:

The process responsible for the change in membrane potential between point 3 and point 4 is the movement of K+ out of the cell.

During an action potential, the depolarization of the membrane occurs when the membrane becomes permeable to Na+, causing an influx of Na+ into the cell. This is followed by the repolarization of the membrane, which is primarily driven by the movement of K+ out of the cell.

During this phase, the membrane becomes hyperpolarized as K+ ions continue to leave the cell. This is a part of the process of repolarization, following the depolarization that occurs due to Na+ influx. Eventually, the movement of K+ restores the cell to its resting membrane potential. The movement of K+ out of the cell restores the cell to its resting potential, or repolarizes it, allowing the cell to fire multiple times without depleting the concentrations of Na+ and K+ ions.