A password will be e-mailed heart shaped ravioli recipe you. Heart Definition The heart is a muscular organ that pumps blood throughout the body. It is located in the middle cavity of the chest, between the lungs. The heart is composed of smooth muscle.

It has four chambers which contract in a specific order, allowing the human heart to pump blood from the body to the lungs and back again with high efficiency. This animation shows the functioning of this extraordinarily complex pump in action. Most heart disease occurs as a result of age or lifestyle. Cholesterol can build up in the arteries as a person gets older, and this is more likely for people who have diets high in saturated fat and cholesterol. Rarely, however, heart disease can also occur due to a virus or bacterium that infects the heart or its protective tissues.