How the Heart Works

Shaped like an upside-down pear and located a little to the left of the middle of your chest, your heart is about the size of your fist and weighs between 7 and 15 ounces. It is a muscle with a very special function: sending blood—which provides oxygen and nutrients—around your body, and carrying away waste.

The heart muscle is like two pumps in one. The right side of the heart receives blood from the body and pumps it to the lungs. The left side of the heart does the opposite: It receives blood from the lungs and pumps it out to the body.

Electrical impulses from your heart muscle cause your heart to contract and pump the blood back and forth between it and your body through the circulatory system—a complex network of arteries and veins. If all the vessels of the circulatory system in your body were laid end-to-end, they would extend about 60,000 miles, enough distance to circle the earth more than twice.

Each day, the average heart beats 100,000 times, pumping about 2,000 gallons of blood around your body. A person’s heart, which beats between 60 and 100 times per minute, may beat more than 2.5 billion times during an average life span.

It takes less than 60 seconds for your heart to pump blood to every cell in your body. Your body needs this steady supply of oxygen-rich blood to keep it working right. If your cells don’t get oxygen, they will die, which in turn, puts you at risk, too.