Permeability of which of these ions is affected by a positive-feedback mechanism once threshold is reached
A)sodium
B)potassium
C)calcium
D)chloride

Question

Quizplus · Accepted Answer

Once the threshold potential is reached in a neuron, sodium channels open and there is a rapid influx of sodium ions which leads to depolarization of the membrane. This depolarization further opens more voltage-gated sodium channels, creating a positive-feedback mechanism which increases the permeability of sodium ions. This positive-feedback mechanism is responsible for the rapid rise of action potentials in neurons. Therefore, sodium ions are the only choice affected by positive-feedback mechanisms once the threshold is reached.

Permeability of Which of These Ions Is Affected by a Positive-Feedback