How the Heart Muscle Pumps Blood

The average human heart beats 100,000 times each day and 36 million times annually. While only the size of a clenched fist, your heart pumps about 2,000 gallons of blood each day and nearly 700,000 gallons each year.

Blood provides the oxygen and nutrients that your organs need to function normally. The left side (left ventricle) of your heart receives oxygen-rich blood from your lungs and pumps it throughout your body. Oxygen-depleted blood is returned to the right side (right ventricle) of your heart. It is then pumped through your lungs where it releases carbon dioxide, receives oxygen and is returned to the left ventricle…and the cycle begins anew.

Source: American Heart Association - Heart, How it Works http://www.americanheart.org/presenter.jhtml?identifier=4642