HEART

The heart, one of the vital organs in the human body, is a powerful pump located behind and slightly to the left of the breastbone and between the lungs. It is a muscle about the size of your fist which contracts and expands using its own bio-electrical system, to continuously pump blood around the body to nourish and provide energy. The pumping of the heart is known as the cardiac cycle, which occurs about 72 times per minute and it pumps blood through network of vessels in the body.

The heart lies at the centre of these complicated network of blood vessels which include arteries and veins. The left side of the heart receives oxygen filled blood from the lungs and pumps it out through the 'arteries' around the body and the right side receives used up-blood containing carbon dioxide through the 'veins' and sends this blood to the lungs to get rid of the carbon dioxide and take in fresh oxygen.

The heart, in the simplest terms, consists of four chambers, two atria (upper chambers) and two ventricles (lower chambers). As the muscles of the heart relax, blood (oxygen filled blood from the lungs and carbon dioxide filled blood from the rest of the body) enters its various chambers. The atrium fill with blood and help move blood into the ventricle.

The ventricle supplies the main force that pumps the blood out, through either the lungs or to the rest of the body. As the blood enters the heart, Flaps called vales close quickly to stop any blood leaking backwards and thus control the direction of blood flow. There are four valves; mitral and the tricuspid between the atria and the ventricles and other two, aortic and pulmonary through which blood enters and leaves the heart.