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Categories > Heart Health > Heart disease: Prevention

How your heart works

Believe it or not, your heart is the hardest-working muscle in your body. This vital organ pumps blood to your brain, nerve and bone cells, and all of the millions of other cells in your body, night and day your whole life—without a break. Understanding the basic anatomy and functioning of the heart helps us appreciate the importance of taking care of this essential organ.

For such a strong muscle with such a large task, your heart isn’t all that big. If you make a fist with one hand and wrap your other hand around it, you’ll get a pretty good idea of your heart’s size and shape.

The heart has four chambers. The upper two are the left and right atria, which serve as filling tanks. The lower two are the left and right ventricles, which do most of the pumping. The right atrium collects blood that has circulated through the body and pushes it into the right ventricle, which pumps the ‘used’ blood through the pulmonary artery to the lungs. There, the blood dumps carbon dioxide, a waste gas, and picks up oxygen. The blood then flows through the pulmonary veins back to the heart, where it collects in the left atrium. From there the blood is pushed into the left ventricle, which pumps it through the aorta, the body’s main artery, to bring oxygen and other nutrients to the rest of the body.

Four valves—the tricuspid, pulmonary, mitral and aortic valves—regulate blood flow into and out of the right and left ventricles. The valves open and snap shut, ensuring that blood doesn’t flow back up into the chamber from which it has just come.

In order to function properly, the heart’s four chambers must beat in a synchronized manner. This process is governed by a series of electrical impulses, or signals, which cause heart cells to contract, making the heart beat. These impulses start in a small bundle of highly specialized cells—the sinoatrial node—located in the right atrium. Normally, electrical signals are generated by this ‘natural pacemaker’ at regular intervals, but emotional reactions and hormonal factors can affect the timing of the impulses.

Although it’s constantly working—beating some 35 million times a year for a person’s whole life—the heart needs periods of intense work—exercise—to keep it in top condition.