The heart s function is to circulate blood .
Blood circulation delivers oxygen and removes carbon dioxide from all of the tissues of the body.
The heart circulates blood by pumping it, and consists of two parallel pumps made of specialized muscle. The left side of the heart receives oxygenated blood from the lungs and pumps it out to the rest of the body. The right side of the heart receives de-oxygenated blood from the body and pumps it to the lungs to absorb new oxygen. These collections of cells, the sinoatrial and atrioventricular nodes, are called pacemakers . There are special conduction fibers extending from the atrioventricular node which distribute the electrical impulses evenly to the ventricular muscle.