What is repolarization of the heart?

As a domain expert in cardiology, I can explain the concept of repolarization in the context of the heart. Repolarization is a critical process in the electrical activity of the heart, which ensures the proper functioning of the cardiac cycle. Repolarization of the heart refers to the return of the membrane potential in cardiac muscle cells back to their resting state after a wave of depolarization has passed. This process is essential for the heart's ability to contract and pump blood effectively. It occurs during the latter part of the cardiac action potential, specifically in the third phase. During the repolarization process, various ion channels in the cell membrane open and close in a coordinated manner. This allows for the movement of ions, such as potassium (K⁺) and calcium (Ca²⁺), across the membrane. The movement of these ions helps to bring the membrane potential back to its resting level, which is typically around -90 millivolts (mV) in cardiac muscle cells. The repolarization process begins after the rapid depolarization that occurs in phase 0 of the action potential. It is completed by the end of phase 3, at which point the cell is ready for the next action potential, ensuring a continuous and rhythmic contraction of the heart.

the process by which the membrane potential of a neuron or muscle cell is restored to the cell's resting potential. In a cardiac muscle cell, the repolarization process begins after phase 0 of the action potential and is completed by the end of phase 3.