During the absolute refractory period, which statement is true?

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Multiple Choice

During the absolute refractory period, which statement is true?

The absolute refractory period is a time when the voltage-gated sodium channels are not available to produce a new action potential because they are either open (during depolarization) or inactivated after opening. Because many Na+ channels are inactivated, another stimulus cannot trigger another AP right away, so depolarization cannot occur immediately. Calcium channel closure to stop contraction isn’t what sets this refractory window, and the membrane can’t be depolarized again immediately during this phase. The state of sodium channels being already open or inactivated best fits what’s happening during this period.

The absolute refractory period is a time when the voltage-gated sodium channels are not available to produce a new action potential because they are either open (during depolarization) or inactivated after opening. Because many Na+ channels are inactivated, another stimulus cannot trigger another AP right away, so depolarization cannot occur immediately. Calcium channel closure to stop contraction isn’t what sets this refractory window, and the membrane can’t be depolarized again immediately during this phase. The state of sodium channels being already open or inactivated best fits what’s happening during this period.

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