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Heart Health Center

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Human Anatomy

Illustration of the human heart

Picture of the Heart

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© 2014 WebMD, LLC. All rights reserved.

The heart is a muscular organ about the size of a fist, located just behind and slightly left of the breastbone. The heart pumps blood through the network of arteries and veins called the cardiovascular system.

The heart has four chambers:

  • The right atrium receives blood from the veins and pumps it to the right ventricle.
  • The right ventricle receives blood from the right atrium and pumps it to the lungs, where it is loaded with oxygen.
  • The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle.
  • The left ventricle (the strongest chamber) pumps oxygen-rich blood to the rest of the body. The left ventricle’s vigorous contractions create our blood pressure.

The coronary arteries run along the surface of the heart and provide oxygen-rich blood to the heart muscle. A web of nerve tissue also runs through the heart, conducting the complex signals that govern contraction and relaxation. Surrounding the heart is a sac called the pericardium.

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