How The Heart Works

The heart is a muscle about the size of a fist. It's function is to pump blood* around the body, without which it would not function.

The heart is divided into four chambers (as illustrated right). The right atrium and ventricle pump deoxygenated blood from the body to the lungs. The left atrium and ventricle pump oxygenated blood from the lungs around the body. As more pressure is needed to pump blood around the body than to the lungs, the muscle wall on the left side of the heart is stronger, so you are likely to feel your heart beating more strongly on the left side

The atria and ventricles are joined by one-way valves (the Mitral and Tricuspid valves) that ensure the blood flows in the right direction.

*Blood is made up of red and white blood cells. The red blood cells' function is to carry oxygen around the body.