What exits the neuron during repolarization?

What exits the neuron during repolarization?

• A. sodium
• B. chloride
• C. potassium
• D. proteins

Answer: (C)

During repolarization, potassium ions exit the neuron. Voltage-gated potassium channels open after the peak of the action potential, allowing K+ to flow out of the cell. This outward movement removes positive charge from the interior, making the inside more negative and bringing the membrane potential back toward the resting level. Sodium rushing in during depolarization is what caused the spike, and those channels inactivate as repolarization occurs. Chloride movement isn’t the main driver of this phase, and proteins don’t exit the neuron to restore the resting potential. The Na+/K+ ATPase helps reestablish the ion gradients over time, but the immediate repolarization is driven by potassium efflux.

During repolarization, potassium ions exit the neuron. Voltage-gated potassium channels open after the peak of the action potential, allowing K+ to flow out of the cell. This outward movement removes positive charge from the interior, making the inside more negative and bringing the membrane potential back toward the resting level. Sodium rushing in during depolarization is what caused the spike, and those channels inactivate as repolarization occurs. Chloride movement isn’t the main driver of this phase, and proteins don’t exit the neuron to restore the resting potential. The Na+/K+ ATPase helps reestablish the ion gradients over time, but the immediate repolarization is driven by potassium efflux.