What organ pumps blood throughout the body?

The heart is the organ that pumps blood throughout the body. It is a muscular organ about the size of a clenched fist, located in the chest between the lungs.

The human heart has four chambers: the right and left atria and the right and left ventricles. The right side sends oxygen-poor blood to the lungs, while the left side pumps oxygen-rich blood through the aorta to the rest of the body. One-way valves help prevent blood from flowing backward.

The heart’s rhythm is controlled by electrical signals that begin in the sinoatrial node, often called the natural pacemaker. Blood carries oxygen and nutrients to tissues and transports carbon dioxide and other wastes away.

A common mix-up is confusing the heart’s role with the lungs’ role. The lungs exchange oxygen and carbon dioxide; the heart circulates the blood that carries those gases.