ARTERIES.

The arteries are the blood vessels that deliver oxygen-rich blood from the heart to the tissues of the body. Each artery is a muscular tube lined by smooth tissue and has three layers:

• The intima, the inner layer lined by a smooth tissue called endothelium
• The media, a layer of muscle that lets arteries handle the high pressures from the heart
• The adventitia, connective tissue anchoring arteries to nearby tissues

The largest artery is the aorta, the main high-pressure pipeline connected to the heart's left ventricle. The aorta branches into a network of smaller arteries that extend throughout the body. The arteries' smaller branches are called arterioles and capillaries. The pulmonary arteries carry oxygen-poor blood from the heart to the lungs under low pressure, making these arteries unique.

Conditions of the Arteries

• Atherosclerosis: The buildup of cholesterol (a waxy substance) into what are called plaques in the arteries' walls. Atherosclerosis in the arteries of the heart, brain, or neck can lead to heart attacks and strokes.
• Vasculitis (arteritis): Inflammation of the arteries, which may involve one or more arteries at the same time. Most vasculitis is caused by an overactive immune system.
• Stenosis of the arteries: Narrowing of the arteries, usually caused by atherosclerosis. When stenosis occurs in arteries in the heart, neck, or legs, the limitations in blood flow can cause serious health problems.
• Arterial thrombosis: A sudden blood clot in one of the arteries, stopping blood flow. Immediate treatment is necessary to restore blood flow in the artery.
• Coronary artery disease: Atherosclerosis with narrowing of the arteries supplying blood to the heart muscle. Coronary artery disease makes a heart attack more likely.