The heart is a muscular organ that pumps blood throughout the body, according to the National Institute of Health. Located near the center of the chest, the muscular portion of the chest is located more on the left side of the chest cavity.
The heart is at the center of all the activity of the circulatory system, which contains arteries, blood vessels and capillaries. As the walls of the heart contract, blood pumps throughout the body, and nearly every activity that takes place in the body relies on the heart and the pumping action. There are also chambers in the heart that ensure blood flows in the correct direction.