The heart is the primary organ of the cardiovascular system. It is a beating muscle that continually pumps blood to the rest of the body. The coronary arteries supply the heart itself with the necessary oxygen and nutrients it needs to function effectively. Red blood cells, white blood cells, and other substances flow freely to the heart and other parts of the body. In a healthy person, the walls of the artery are smooth and uniform in thickness. Over time, however, a high level of circulating