The Heart and Its Electrical System

The Heart and Its Electrical System

h9991360_001.jpg

The heart has four chambers. The two upper chambers are called atria (the right atrium and the left atrium), and the two lower chambers are called ventricles.

h9991262_001_1.jpg

Normally, the heartbeat starts in the right atrium in a group of special heart cells called the sinoatrial (or sinus) node. These cells act as a pacemaker for the heart.

The heart's pacemaker sends out an electrical signal (impulse) that spreads throughout the heart along electrical pathways. These pathways transmit the signal from the upper to the lower chambers of the heart, which causes the heart muscle to contract. Regular, rhythmic electrical signals keep the heart pumping blood to the lungs and the body.

Credits

ByHealthwise Staff

Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine

Specialist Medical ReviewerRakesh K. Pai, MD, FACC - Cardiology, Electrophysiology

Current as ofMarch 12, 2014

WebMD Medical Reference from Healthwise
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.© 1995-2015 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.