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How a healthy heart looks (anatomy)

The normal, healthy heart is a muscle about the size of an adult fist. It weighs about one pound.

The heart is located near the middle of your chest, slightly to the left. It is a tough muscle designed to work hard and continuously during your life.

The heart's main "job" is to pump blood that carries oxygen and nutrients throughout your body through miles of tubes or blood vessels.

diagram of a normal heart

Your heart is enclosed in a protective, fiber-like sac called the pericardium. Just like other muscles in your body, your heart needs blood to do its work.

Blood is supplied by two large blood vessels and their branches called coronary arteries. These arteries are on the outside of the heart muscle.

If these arteries are blocked, as in coronary artery disease, the blood flow to the heart can be reduced or stopped. This causes pain and if a part of the heart muscle goes without blood for a time, it will die. This is what happens when you have a heart attack.

Diagram of a normal heart shows how blood flows from the right atrium through the tripcuspid valve to the right ventricle and then up through the pulmonary valve. Blood goes from the left atrium, through mitral valve to the left ventricle and the up through the aortic valve.

Your right coronary artery supplies the bottom and back of your heart.

Your left coronary artery divides into two large blood vessels called the left anterior descending and the circumflex. It supplies blood to the back, left side, and front of your heart.

Each side of your heart has two chambers, an upper one (called an atrium) and a lower one (called a ventricle). Between each chamber are valves that work like valves on a mechanical pump: they keep fluid (in this case, your blood) moving in the right direction. The four valves are:

  • Your tricuspid valve allows blood to flow from the right atrium to the right ventricle.
  • Your pulmonary valve allows blood to flow from your right ventricle to your lungs through your pulmonary artery.
  • Your mitral valve allows blood to flow from your left atrium to your left ventricle.
  • Your aortic valve allows blood to flow from your left ventricle to all parts of your body through your aorta.

How a healthy heart works (physiology)

The pumping system of your heart is powered by an electrical system that is naturally programmed to tell the heart to beat about 60 to 100 times per minute (in an adult).

To make a heartbeat, an electrical impulse starts in a spot in your upper heart called the sinoatrial (SA) node and travels through the atrium down to a spot between the atria and ventricles, called the atrioventricular (AV) node.

From the AV node, the impulse travels through the ventricles. When the impulse travels through the atria, it causes them to contract (squeeze) and send blood to the ventricles.

When the impulse travels through the ventricles it causes them to contract and send blood to the body. It is important for the atria and ventricles to contract in a coordinated way to prevent problems.

The right side of your heart receives blood through the veins and pumps it to the lungs to receive new oxygen. The large blood vessel that carries blood from the heart to the lungs is the pulmonary artery.

The left side receives blood with new oxygen from the lungs and sends it out to the body. The large blood vessel that carries blood from the heart to the body is the aorta.



Source: Allina Health's Patient Education Department, Helping Your Heart, fourth edition, cvs-ahc-90648

First published: 10/04/2002
Last updated: 06/01/2007

Reviewed by: Allina Health's Patient Education Department experts