Question

The falling phase of the action potential is due primarily to

A. Na+ flow in the cell only.

B. Na+ flow out of the cell only.

C. K+ flow out of the cell only.

D. K+ flow into the cell only.

E. Na+ flow out of the cell and K+ flow into the cell.

Answer 1

The falling phase of the action potential is primarily due to the flow of C) potassium ions (K+) out of the cell. Hence, C) is correct.

Step-by-step explanation:

The falling phase of the action potential is primarily due to the flow of potassium ions (K+) out of the cell. During the depolarization phase of the action potential, sodium ions (Na+) flow into the cell, leading to a reversal in charge across the membrane.

This depolarization opens voltage-gated potassium channels, allowing K+ ions to flow out of the cell. The outflow of K+ ions causes repolarization and restores the resting potential of the cell.