How your heart works
Your heart is a muscle. Its main "job" is to pump blood rich in oxygen and nutrients through miles of blood vessels in your body. All cells in your body need oxygen to survive.
Did you know?
Your heart is about the size of an adult fist and it weighs about 1 pound.
Each side of your heart has two chambers: an upper one (called an atrium) and a lower one (called a ventricle). Between each chamber are valves that keep your blood moving in the right direction.
Two blood vessels and their branches, called coronary arteries, supply blood to your heart. These arteries are on the outside of your heart.
Your heart also has an electrical system, which powers your heart’s pumping system. A group of special cells sends an electrical impulse through your heart muscle causing it to contract, or beat, about 60 to 100 times per minute.
These special cells are called the sinoatrial (SA) node and the atrioventricular (AV) node.