How Your Heart Works

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Your heart is a strong, muscular pump. In a 70-year lifetime, an average human heart beats more than 2.5 billion times.

Your heart is a muscle about the size of your fist. It is made up of four chambers: the right atrium, right ventricle, left atrium and left ventricle. The right side of the heart receives blood that is low in oxygen from veins all over the body. It pumps this blood into the lungs where it becomes re-oxygenated. The left side of the heart receives this oxygen-rich blood from the lungs. It pumps the blood back out to the rest of the body.

While blood is circulating through the body, it delivers oxygen and nutrients to tissue through the capillaries and, at the same time, picks up carbon dioxide and other waste materials. The veins return the deoxygenated blood to the heart and the cycle begins again.

Why Heart Failure Occurs

Heart failure happens when your heart muscle becomes weak and is unable to pump enough to meet your body’s need for blood and oxygen. Typically, the lower chambers of the heart, called the ventricles, do not beat efficiently like they do in a healthy heart. Heart failure can get worse if it is not treated.


Recommended animations:

  • Introduction: Inside a Healthy Heart
  • Understanding Heart Failure: Heart Failure Explained

View Understanding Heart Failure and Treatment Options Animations