In the normal heart, the contraction of the heart's tissues, which pump blood to the lungs and body, is timed by the movement of electrical impulses. These proceed from the brain to the Sinoatrial Node, through the atria to the Atrioventricular Node, and then through the muscles of the ventricles by means of the Purkinje Fibers.
As electrical impulses travel through the heart muscles, they contract, forcing blood into the pulmonary artery and aorta (not shown). Click for more about Electrophysiology.
