During the absolute refractory period, which statement best describes the state of sodium channels?

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Multiple Choice

During the absolute refractory period, which statement best describes the state of sodium channels?

During the absolute refractory period, voltage-gated sodium channels are inactivated and cannot reopen, so another action potential cannot be produced regardless of stimulus. This phase starts right after the initial depolarization and lasts until most Na+ channels recover from inactivation and return to the resting, activatable state. Saying the channels are already open or inactivated reflects that they are not in a state ready to open again; the inactivated state is what blocks a new impulse. The other options don’t fit because depolarizing again isn’t possible while Na+ channels are inactivated, and calcium channel behavior isn’t the defining factor here.

During the absolute refractory period, voltage-gated sodium channels are inactivated and cannot reopen, so another action potential cannot be produced regardless of stimulus. This phase starts right after the initial depolarization and lasts until most Na+ channels recover from inactivation and return to the resting, activatable state. Saying the channels are already open or inactivated reflects that they are not in a state ready to open again; the inactivated state is what blocks a new impulse. The other options don’t fit because depolarizing again isn’t possible while Na+ channels are inactivated, and calcium channel behavior isn’t the defining factor here.

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