How does the heart pumping?

Answer 1

Magically.

Answer 2

The heart pumps by periodically compressing itself. It is a muscle. There are four chambers; the right and left atria, and the right and left ventricles. The cycle starts in the SA node, a bundle of nerves near the right atrium. The right atrium contracts followed almost immediately by the left atrium. Each atrium forces its blood contents into its respective ventricle. The right atrium takes blood from the body and the left atrium takes blood from the lungs. A short period of time later, the right ventricle contracts followed almost immediately by the left ventricle. The right ventricle supplies blood to the lungs, while the left ventricle supplies blood to the body. There are six valves surrounding these four chambers that force the blood flow to only go in one direction.