Atherosclerosis is a progressive disease of blood vessels that is responsible fo

The disease process involves several stages and usually affects the aorta and coronary arteries. The initial event involves damage to the tunica intima caused by bloodborne chemicals or physical factors such as a mechanical stress from hypertension or infection. Injured endothelial cells release chemicals that increase the uptake by the endothelium of fats, LDLs, and cholesterol. This eventually attracts macrophages that ingest the oxidized fats and, along with smooth muscle cells from the tunica media, transform into foam cells. Foam cells become fatty streaks, which, along with collagen and elastin fibers secreted by smooth muscle cells, form atherosclerotic plaques. These protrude into the lumen and narrow the blood vessels.