Question

Physiology of the nerve impulses: What occurs at the peak of the action potential during the falling phase? a) Voltage-gated K+ channels open

b) Voltage-gated Na+ channels become inactivated
c) Membrane hyperpolarization
d) Activation of the Na+/K+ pump

Answer 1

At the peak of the action potential, voltage-gated K+ channels open allowing K+ to exit the cell while voltage-gated Na+ channels become inactivated, leading to the falling phase and subsequent hyperpolarization.

Step-by-step explanation:

During the peak of the action potential, right after the membrane has depolarized, voltage-gated Na+ channels become inactive as part of the cell's ways to stop the influx of Na+. Almost simultaneously, voltage-gated K+ channels open, allowing K+ to leave the cell. This outflow of K+ begins the process of repolarization where the membrane potential starts to return to a more negative value inside the cell. Then, the membrane often overshoots to a more negative value than the original resting potential in a phase called hyperpolarization.

These events help to reset the neuronal membrane potential and prepare the neuron for another action potential. This refractory period ensures that action potentials only travel in one direction and that they are clearly separated from each other.