Action potentials
A) initially cause depolarization of the membrane, usually followed by hyperpolarization.
B) cause a return to resting potential when the sodium channels open.
C) can be triggered in rapid succession, with no measurable delay between spikes.
D) are initiated by the membrane's increased permeability to potassium.
E) result from inactivation of leak channels.

Question

Quizplus · Accepted Answer

Action potentials initially cause depolarization of the membrane, which is followed by hyperpolarization. During depolarization, the membrane potential becomes less negative, and during hyperpolarization, the membrane potential becomes more negative than the resting potential.

B, C, D, and E are incorrect. B is incorrect because action potentials do not cause a return to resting potential when the sodium channels open. Instead, during depolarization, the sodium channels open, causing an influx of sodium ions that depolarizes the membrane. C is incorrect because there is a measurable delay between action potentials, known as the refractory period. D is incorrect because the increase in membrane permeability to sodium, not potassium, initiates the action potential. E is incorrect because leak channels, which are always open, do not play a role in generating action potentials.

Action Potentials