Difficulty: Hard

Average Score: 42%

Which of the following actions contributes to the repolarization of a neuron?

Rationale

Opening of potassium channels to allow potassium to leave the neuron.

During the repolarization phase of an action potential, the opening of potassium channels allows potassium ions to exit the neuron, which helps restore the negative membrane potential after depolarization. This efflux of positively charged potassium ions is crucial for returning the neuron's membrane potential to its resting state.

A (Inhibition of sodium and potassium pumps to stop all ion movement into the neuron.) YOUR ANSWER

Inhibiting the sodium and potassium pumps would prevent the active transport of ions necessary for maintaining the resting membrane potential and would not contribute to repolarization. Instead, it would lead to the accumulation of sodium inside the neuron and hamper the restoration of the negative charge.

C (Closing of both sodium and potassium channels to restrict the movement of ions into and out of the neuron.) YOUR ANSWER

While closing sodium channels is a part of repolarization, closing potassium channels would inhibit the efflux of potassium ions, preventing repolarization from occurring effectively. This action would impede the necessary process of returning the membrane potential to its resting state.

D (Opening of sodium channels to allow sodium to enter the neuron.) YOUR ANSWER

Opening sodium channels facilitates depolarization rather than repolarization since it allows sodium ions to flow into the neuron, making the inside more positive. This action counteracts the process of repolarization, which requires the movement of potassium ions out of the neuron to restore the negative membrane potential.

Conclusion

Repolarization of a neuron is primarily achieved through the opening of potassium channels, which facilitates the exit of potassium ions, thereby restoring the negative charge inside the neuron after an action potential. The other options either inhibit this process or promote depolarization, highlighting the essential role of potassium efflux in returning the neuron's membrane potential to its resting state.

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