The electrical impulse that initiates a cardiac contraction is called what?

The electrical impulse that initiates a cardiac contraction is called what?

• A. Depolarization
• B. Repolarization
• C. Hyperpolarization
• D. Resting potential

Answer: (A)

Depolarization is the electrical event that starts a cardiac contraction. When the cell membrane becomes less negative (more positive) as voltage-gated channels open, the depolarization wave spreads through the heart, triggering calcium entry and the contraction of cardiac muscle fibers. The impulse that begins this sequence often starts in the sinoatrial node and travels through the conduction system to coordinate the beat. Repolarization is the return of the membrane to its resting negative value after the peak of the action potential, hyperpolarization is when the membrane becomes more negative than the resting potential, and resting potential is the baseline negative charge when the cell is not excited. Thus, the initiating electrical event that leads to contraction is depolarization.

Depolarization is the electrical event that starts a cardiac contraction. When the cell membrane becomes less negative (more positive) as voltage-gated channels open, the depolarization wave spreads through the heart, triggering calcium entry and the contraction of cardiac muscle fibers. The impulse that begins this sequence often starts in the sinoatrial node and travels through the conduction system to coordinate the beat.

Repolarization is the return of the membrane to its resting negative value after the peak of the action potential, hyperpolarization is when the membrane becomes more negative than the resting potential, and resting potential is the baseline negative charge when the cell is not excited. Thus, the initiating electrical event that leads to contraction is depolarization.