MCAT Biological and Biochemical Foundations of Living Systems Practice Exam

The process that describes the shift back to a resting membrane potential after depolarization is known as repolarization. During depolarization, the membrane potential becomes more positive due to the influx of sodium ions into the neuron. To return to a resting state, the cell must be repolarized.

This is achieved primarily through the efflux of potassium ions from the cell, which occurs when voltage-gated potassium channels open. As potassium ions leave the cell, the internal environment becomes less positive, thus returning the membrane potential toward its resting level.

Repolarization is a crucial part of the action potential mechanism in neurons and muscle cells, ensuring that the cells can properly reset after an excitatory event. Understanding this process is fundamental in studying how signals are transmitted in excitable tissues.