To repolarize the membrane during an action potential, what must occur?

To repolarize the membrane during an action potential, what must occur?

• A. Ligand-gated Na+ ion channels should open
• B. Voltage-gated Na+ ion channels should open
• C. Voltage-gated K+ ion channels should open
• D. Two of the above

Answer: (C)

Repolarization during an action potential is primarily driven by the opening of voltage-gated K+ ion channels. When an action potential is initiated, the membrane is depolarized due to the rapid influx of sodium ions through voltage-gated sodium channels. After the peak of the action potential, these sodium channels begin to close, and the voltage-gated potassium channels open in response to the changes in membrane potential. The opening of the voltage-gated K+ channels allows potassium ions to flow out of the cell, which helps to restore the negative resting membrane potential. This efflux of potassium ions brings the membrane potential back towards the threshold, thereby repolarizing it and completing the action potential. This mechanism is crucial because it ensures that the neuron can reset its membrane potential, allowing for subsequent action potentials to occur. The other choices involve processes tied to different phases of action potentials or signaling pathways, thus making the opening of voltage-gated K+ channels the correct and essential step for repolarization.

Repolarization during an action potential is primarily driven by the opening of voltage-gated K+ ion channels. When an action potential is initiated, the membrane is depolarized due to the rapid influx of sodium ions through voltage-gated sodium channels. After the peak of the action potential, these sodium channels begin to close, and the voltage-gated potassium channels open in response to the changes in membrane potential.

The opening of the voltage-gated K+ channels allows potassium ions to flow out of the cell, which helps to restore the negative resting membrane potential. This efflux of potassium ions brings the membrane potential back towards the threshold, thereby repolarizing it and completing the action potential.

This mechanism is crucial because it ensures that the neuron can reset its membrane potential, allowing for subsequent action potentials to occur. The other choices involve processes tied to different phases of action potentials or signaling pathways, thus making the opening of voltage-gated K+ channels the correct and essential step for repolarization.