Question

Which of the following statements are TRUE about nerve action potentials?

A) A nerve membrane is only polarized when conducting an action potential.
B) Depolarization cannot be conducted from one stretch of nerve membrane to another.
C) Phosphorus ions flowing into the cell cause depolarization.
D) Potassium ions flowing out of the cell cause repolarization.

Answer 1

The True statement about nerve action potentials is 'D) Potassium ions flowing out of the cell cause repolarization.' Depolarization is initiated by sodium ions entering the cell, and the action potential propagates along the neuron membrane.

Step-by-step explanation:

The statement 'D) Potassium ions flowing out of the cell cause repolarization' is TRUE about nerve action potentials. During an action potential, depolarization occurs when the neuron membrane becomes permeable to sodium ions (Na⁺), allowing them to flow into the cell, which makes the internal voltage more positive. This is followed by repolarization, during which potassium ions (K⁺) flow out of the neuron, restoring the negative internal voltage. The nerve membrane is polarized at rest, not just during an action potential. Action potentials are propagated along the nerve membrane as depolarization at one point affects the permeability of the adjacent membrane, allowing the action potential to move along the cell.