A positive feedback loop occurs when the outcome of an event causes the event to continue occurring and amplifies its effects. Which of the following aspects of an action potential constitutes a positive feedback loop?
A)An initial flow of sodium ions into the neuron opens voltage-gated sodium channels, rapidly causing more sodium to enter.
B)Opening of voltage-gated sodium channels causes voltage-gated potassium channels to open and release potassium to the extracellular environment, slowly counteracting sodium influx.
C)The sodium-potassium pump exactly balances ion leaks by pumping three sodium and two potassium ions across the membrane.
D)The threshold potential is around -55mV.

Question

Quizplus · Accepted Answer

The initial flow of sodium ions into the neuron causes more voltage-gated sodium channels to open, which in turn allows even more sodium ions to enter the neuron. This amplifies the depolarization of the neuron and causes the action potential to continue propagating along the axon.

A Positive Feedback Loop Occurs When the Outcome of an Event