International Veterinary Chiropractic Association (IVCA) Practice Exam

Hyperpolarization makes the inside of the cell more negative than its resting state. This happens when extra positive ions leave the cell or negative ions enter, such as increased potassium conductance or chloride conductance. The membrane potential thus moves to more negative values (for example, from around -70 mV toward -80 mV or even more negative). Because the inside is more negative, it becomes harder for a stimulus to reach the threshold for firing an action potential, reducing excitability. Choices that describe depolarization (more positive), no change, or large fluctuations don’t match what hyperpolarization does to the membrane potential.