The heart’s electrical system orchestrates each heartbeat through a precisely timed sequence of electrical signals, ensuring coordinated contractions that pump blood efficiently. This system includes specialized cells and pathways that regulate heart rate and rhythm.

Electrical Conduction Pathway

1. Sinoatrial (SA) node
   • Acts as the heart’s natural pacemaker, generating electrical impulses 60–100 times per minute.
   • Located in the right atrium, it initiates each heartbeat by sending signals through the atria.
   • Heart rate adjusts through autonomic nervous system input (e.g., increases during exercise).
2. Atrioventricular (AV) node
   • Delays the electrical impulse by ~0.1 seconds, allowing atria to fully contract and fill ventricles before ventricular contraction begins.
3. Bundle of His and Purkinje fibers
   • The impulse travels from the AV node through the bundle of His, which splits into left and right bundle branches.
   • Purkinje fibers rapidly distribute the signal to ventricular muscle cells, triggering synchronized ventricular contractions.

Key Features

• Chamber coordination: Atria contract just before ventricles, optimizing blood flow.
• Self-regulation: Backup pacemakers in the AV node or ventricles can maintain a slower rhythm if the SA node fails.
• Rate variability: Normal resting heart rate decreases with age, ranging from 60–100 bpm in adults.

This system ensures the heart adapts to physiological demands while maintaining rhythm stability. Disruptions in any component can lead to arrhythmias, often managed with devices like pacemakers.