NEET Class neet Answered

The pumping action of the heart is regulated by an electrical conduction system that coordinates the contraction of the various chambers of the heart.

1. SA node (sinoatrial node) –The impulse starts in a small bundle of specialized cells located in the right atrium, called the SA node. The electrical activity spreads through the walls of the atria and causes them to contract. This forces blood into the ventricles. The SA node sets the rate and rhythm of the heartbeat.
2. AV node (atrioventricular node). The AV node is a cluster of cells in the center of the heart between the atria and ventricles, and acts like a gate that slows the electrical signal before it enters the ventricles. This delay gives the atria time to contract before the contraction of the ventricles.
3. His-Purkinje Network. This pathway of fibers sends the impulse to the muscular walls of the ventricles and causes them to contract. This forces blood out of the heart to the lungs and body.
4. The SA node fires another impulse and the cycle begins again.