When the measured potential of a membrane reaches threshold,
A) potassium rapidly enters the cell.
B) potassium rapidly leaves the cell.
C) sodium rapidly enters the cell.
D) sodium rapidly leaves the cell.

Question

Quizplus · Accepted Answer

When the measured potential of a membrane reaches threshold, sodium channels open and allow sodium ions to rapidly enter the cell, causing depolarization. This is known as the threshold potential and is the point at which an action potential is initiated.

When the Measured Potential of a Membrane Reaches Threshold