During the relative refractory phase,
A) voltage-gated sodium channels are open.
B) all gated channels are closed.
C) no amount of stimulation can induce another action potential.
D) the neuron is briefly hyperpolarized.

Question

Quizplus · Accepted Answer

During the relative refractory phase, the neuron is briefly hyperpolarized, making it more difficult to generate another action potential. This is due to the presence of some open potassium channels and a slow-closing calcium channel, which prevent the neuron from reaching the threshold for firing another action potential. While some voltage-gated sodium channels may be inactivated during this phase, they are not open, as they would be during the rising phase of the action potential. Therefore, choice A is incorrect. While it may be more difficult to induce another action potential during the relative refractory phase, it is not impossible, so choice C is also incorrect. Finally, choice B is incorrect, as some gated channels, such as the potassium channels mentioned earlier, are still open during this phase.

During the Relative Refractory Phase