1. Sinoatrial (SA) Node: This is the heart's natural pacemaker, located in the right atrium. It initiates the electrical impulse that triggers each heartbeat.
2. Atrial Myocardium: The impulse spreads rapidly through the atrial muscle, causing the atria to contract and pump blood into the ventricles.
3. Atrioventricular (AV) Node: The impulse reaches the AV node, located near the junction of the atria and ventricles. The AV node slows down the impulse slightly, allowing the ventricles to fill with blood.
4. Bundle of His: The impulse travels through the Bundle of His, a specialized band of fibers that extends from the AV node down the interventricular septum (the wall between the ventricles).
5. Right and Left Bundle Branches: The Bundle of His divides into the right and left bundle branches, which carry the impulse to the ventricles.
6. Purkinje Fibers: The bundle branches further divide into a network of fine fibers called Purkinje fibers, which distribute the impulse throughout the ventricular myocardium.
7. Ventricular Myocardium: The impulse stimulates the ventricular muscle, causing it to contract and pump blood out of the heart.
Simplified:
* SA Node (Pacemaker) -> Atria -> AV Node -> Bundle of His -> Bundle Branches -> Purkinje Fibers -> Ventricles
This organized sequence ensures that the heart contracts in a coordinated way, effectively pumping blood throughout the body.
