Cardiac action potential
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Cardiac Action Potential
The Cardiac Action Potential (pronounced: kahr-dee-ak ak-shun po-ten-shul) is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. This event is crucial in the functionality of the heart, as it plays a significant role in the contraction of the heart muscle.
Etymology
The term "Cardiac Action Potential" is derived from the Greek word "kardia", meaning heart, and the Latin words "actio", meaning action, and "potentia", meaning power.
Process
The process of the Cardiac Action Potential involves five phases (0-4), each characterized by specific ionic movements across the cardiomyocyte membrane.
- Phase 0: This is the rapid depolarization phase. It is initiated by the opening of voltage-gated sodium channels.
- Phase 1: This is the initial repolarization phase. It is characterized by the closure of sodium channels and the opening of potassium channels.
- Phase 2: This is the plateau phase. It is marked by the balance between inward movement of calcium ions and outward movement of potassium ions.
- Phase 3: This is the rapid repolarization phase. It is characterized by the closure of calcium channels and continued opening of potassium channels.
- Phase 4: This is the resting membrane potential phase. It is maintained by the sodium-potassium pump.
Related Terms
- Depolarization: The process by which the membrane potential of a cell shifts towards zero.
- Repolarization: The process by which the membrane potential of a cell returns to its resting state after depolarization.
- Hyperpolarization: The process by which the membrane potential of a cell becomes more negative than its resting potential.
- Refractory period: The period of time during which a cell is incapable of repeating an action potential.
See Also
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