The heart is a hollow muscular organ that acts as a pump and is responsible for the circulation of the blood. The heart is cone shaped, with the point downwards, and is situated behind the lungs. A septum divides the heart into right and left valves, each of which is further divided into an upper chamber, known as an atrium, and a lower one, called a ventricle. Four valves control the direction of the blood flow at each outlet.
