Electrophysiology Unit Practice Exam 2026 – The Comprehensive All-in-One Guide to Exam Success!

Repolarization is the phase after the spike when the membrane potential moves back toward the resting negative value. This happens as potassium channels open and potassium exits the cell, while sodium channels reset, making the inside of the cell less positive again. Returning toward the resting potential reinstates the cell’s baseline excitability and sets the stage for future depolarization when the threshold is reached. That’s why this option—describing the action potential returning to its resting state—is the best fit. The other descriptions refer to depolarization, pushing the membrane to positive values, or continuing depolarization, which aren’t what repolarization accomplishes.