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Your Heart’s Electrical System

The heart has a special system that creates and sends electrical signals. First, signals tell the 2 upper chambers (atria) to squeeze. This moves blood to the 2 lower chambers (ventricles). Next, electrical signals tell the ventricles to squeeze. This moves blood to the lungs and body.

Front view of heart showing atria on top and ventricles on bottom. Aorta is large artery exiting heart at top. SA node and AV node are in right atrium. Bundle branch nerves are in wall between ventricles and curve into ventricle walls. Signals from AV node travel to AV node and into bundle branches.

Electrical Signals

Groups of special cells in the right atrium, called nodes, send out the heart’s electrical signals. The signals travel along pathways. In the ventricles, these pathways are called bundle branches.

The SA Node

This sets the pace of the heartbeat. It starts each beat by releasing a signal telling the atria to squeeze.

The AV Node

This receives the signal from the atria. It is the “gateway” between the atria and the ventricles. The AV node channels the signal into the ventricles.

The Bundle Branches

These carry the signal through the ventricle walls. As the signal moves through the ventricles, the ventricles squeeze.

Online Medical Reviewer: Foster, Sara, RN, MPH
Online Medical Reviewer: MMI board-certified, academically affiliated clinician
Date Last Reviewed: 3/5/2014
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