Atherosclerosis - Description

The arteries are blood vessels that carry blood from the heart to all parts of the body. Arteries are made up of several layers of tissue that are normally soft and pliable. The layers must be able to expand and contract as blood passes through them.

Arteries often become leathery and rigid. When that happens, blood may flow less easily through the arteries. The hardening of arteries is called arteriosclerosis. Many factors can cause arteriosclerosis. Normal aging, high blood pressure, and certain diseases, such as diabetes (see diabetes mellitus entry), are common causes of arteriosclerosis.

Atherosclerosis is a special form of arteriosclerosis. In atherosclerosis, only the inner lining of the artery is affected. Fatty materials deposit on the lining of the artery, forming a larger and larger mass. The mass is usually called a plaque (pronounced PLAK). It becomes more and more difficult for blood to flow through the artery. Eventually the artery may close completely.

The formation of a plaque in an artery can lead to a number of cardiovascular (heart and blood vessel) problems. If the plaque forms in an artery that leads to the heart, it may block the flow of blood to the heart, and a heart attack may occur. If the plaque occurs in an artery that leads from the heart, it may prevent the brain from getting the blood and oxygen it needs. The result is a stroke (see stroke entry).

The plaque may also break off from the artery wall and travel through the bloodstream. It may then block an artery somewhere else in the body, a process known as thrombosis. A thrombosis that blocks an artery in the heart produces a condition known as a coronary thrombosis.

Atherosclerosis can occur anywhere in the body. It can affect arteries of the neck, kidneys, thighs, and arms. In such cases, the interruption of blood flow can produce many medical conditions, such as kidney failure and gangrene (death of tissue).