Tiny electric currents flow through the heart muscle and cause them to contract, squeezing blood throughout the body. This animation shows the electrical system of the heart and how it is driven by a small patch of tissue called the cardiac pacemaker or sinoatrial node.

Provides an overview of the circulatory system including the blood vessels that supply the heart. When these coronary arteries become blocked, the vessels need to be bypassed with other blood vessels. The animation describes a coronary artery bypass graft surgery or CABG.