How does the heart trigger a coordinated beat?Understand normal cardiac electrical activity

The heart triggers a coordinated beat through a complex system of electrical signals. Here's a step-by-step explanation:

1. The process begins in the sinoatrial (SA) node, also known as the heart's natural pacemaker. The SA node is located in the right atrium, one of the heart's two upper chambers.

2. The SA node sends an electrical signal across the atria, causing them to contract and pump blood into the heart's two lower chambers, the ventricles.

3. The signal then reaches the atrioventricular (AV) node, which is located between the atria and the ventricles. There is a slight delay here to allow the atria to fully contract before the ventricles do.

4. From the AV node, the signal travels along a pathway of fibers called the bundle of His. This pathway divides into two branches that lead to the left and right ventricles.

5. The signal spreads across the cells of the ventricle walls, causing them to contract and pump blood out to the lungs or the rest of the body.

6. After the ventricles contract, they need to refill with blood. During this time, the electrical system in the heart resets itself in preparation for the next heartbeat.

This process repeats in a cycle, causing the heart to beat in a coordinated and rhythmic manner. Any disruption in this electrical system can lead to a heart rhythm disorder, or arrhythmia.