How the Body Works: The Heart

The heart is a muscular organ which pumps blood throughout the body. The continuous driving force is generated by the action of cardiac muscle-a specialized form of muscle. The muscle is arranged as whorls of tissue surrounding the two cavities of the ventricles. The left ventricle is larger as it is required to pump blood around the general circulatory system. The right ventricle only pumps blood along the shorter circuit through the lungs. The autonomic nervous system controls changes in the rate of heartbeat.