In the first phase of triggering an action potential in a neuron, Na⁺ ions flow in and
A) only trigger a negative feedback loop.
B) only trigger a positive feedback loop.
C) only activate the sodium/potassium pump.
D) trigger a negative feedback loop and activate the sodium/potassium pump.
E) trigger a positive feedback loop and activate the sodium/potassium pump.

Question

Quizplus · Accepted Answer

During the first phase of triggering an action potential in a neuron, Na⁺ ions flow in through voltage-gated sodium channels. This influx of Na⁺ ions depolarizes the membrane, making it more positive. This positive feedback loop leads to the opening of more voltage-gated sodium channels and further influx of Na⁺ ions, resulting in the rapid depolarization of the membrane and the initiation of an action potential. The activation of the sodium/potassium pump comes later during the repolarization phase to restore the original ion distribution.

In the First Phase of Triggering an Action Potential in a Neuron