Question

In what period can a neuron NOT respond to a second stimulus?

(a) Absolute refractory period
(b) Relative refractory period

Answer 1

During the absolute refractory period, a neuron cannot respond to a second stimulus as the voltage-gated Na+ channels are inactivated.

Step-by-step explanation:

A neuron cannot respond to a second stimulus during the absolute refractory period. This period is the time following an action potential when the voltage-gated Na+ channels are inactivated, preventing the initiation of a new action potential, regardless of the strength of the stimulus. This phase allows ion channels to return to their resting state. The relative refractory period, in contrast, is a phase when a new action potential can be initiated but requires a stronger-than-normal stimulus because the voltage-gated K+ channels are still open.

Answer 2

The period in which a neuron cannot respond to a second stimulus is called the absolute refractory period.

Step-by-step explanation:

The period in which a neuron cannot respond to a second stimulus is called the absolute refractory period. During this period, another action potential cannot be generated because the voltage-gated Na+ channel is inactivated. Once the channel returns to its resting conformation, a new action potential can be initiated, but only by a stronger stimulus than the previous one. This is due to the flow of K+ ions out of the cell, preventing Na+ ions from depolarizing the cell.