Atherosclerosis
Created | Updated Jan 28, 2002
What is atherosclerosis?
Atherosclerosis comes from the Greek words athero (meaning gruel or paste) and sclerosis (hardness). It involves deposits of fatty substances, cholesterol , cellular waste products, calcium and other substances in the inner lining of an artery. This build-up is called plaque.
[Arteriosclerosis is a general term for the thickening and hardening of arteries. Some hardening of arteries normally occurs when people grow older.]
Plaque may partially or totally block the blood's flow through an artery. Two things that can happen where plaque occurs are
bleeding (hemorrhage) into the plaque.
the plaque ruptures and a blood clot (thrombus) forms on the plaque's surface.
If either of these occurs and blocks the entire artery, a heart attack or stroke may result. Atherosclerosis affects large and medium-sized arteries. The type of artery and where the plaque develops varies with each person.
Atherosclerosis is a slow, progressive disease that may start in childhood. In some people this disease progresses rapidly in their third decade. In others it doesn't become threatening until they're in their fifties or sixties.
How does atherosclerosis start?
It's a complex process. Exactly how atherosclerosis begins or what causes it isn't known, but some theories have been proposed.
Many scientists think atherosclerosis begins because the innermost layer of the artery becomes damaged. This layer is called the endothelium .
Three possible causes of damage to the arterial wall are:
elevated levels of cholesterol and triglyceride in the blood,
high blood pressure and
tobacco smoke.
Tobacco smoke greatly worsens and speeds up the growth of atherosclerosis in the coronary arteries , the aorta and arteries in the legs. (The coronary arteries bring blood to the heart muscle; the aorta is the large vessel that the heart pumps blood into to take to the body.) Because of the damage, over time fats, cholesterol, fibrin, platelets, cellular debris, calcium and other substances are deposited in the artery wall. These substances may stimulate the cells of the artery wall to produce still other substances that result in further accumulation of cells in the innermost layer of the artery wall where the atherosclerotic lesions form. These cells accumulate and many of them divide. At the same time, fat builds up within and around these cells. They also form connective tissue.
The innermost layer of the artery (the endothelium) becomes markedly thickened by these accumulating cells and surrounding material. If it's thickened enough, the diameter of the artery will be reduced and the blood flow decreased, thus reducing the oxygen supply. If the blood supply to the heart muscle is reduced, a heart attack can occur. If the blood supply to the brain is cut off, a stroke can occur. And if the blood supply to the arms and legs is reduced, gangrene can result.
Often a blood clot forms and blocks the artery, stopping the flow of blood.
Atherosclerosis comes from the Greek words athero (meaning gruel or paste) and sclerosis (hardness). It involves deposits of fatty substances, cholesterol , cellular waste products, calcium and other substances in the inner lining of an artery. This build-up is called plaque.
[Arteriosclerosis is a general term for the thickening and hardening of arteries. Some hardening of arteries normally occurs when people grow older.]
Plaque may partially or totally block the blood's flow through an artery. Two things that can happen where plaque occurs are
bleeding (hemorrhage) into the plaque.
the plaque ruptures and a blood clot (thrombus) forms on the plaque's surface.
If either of these occurs and blocks the entire artery, a heart attack or stroke may result. Atherosclerosis affects large and medium-sized arteries. The type of artery and where the plaque develops varies with each person.
Atherosclerosis is a slow, progressive disease that may start in childhood. In some people this disease progresses rapidly in their third decade. In others it doesn't become threatening until they're in their fifties or sixties.
How does atherosclerosis start?
It's a complex process. Exactly how atherosclerosis begins or what causes it isn't known, but some theories have been proposed.
Many scientists think atherosclerosis begins because the innermost layer of the artery becomes damaged. This layer is called the endothelium .
Three possible causes of damage to the arterial wall are:
elevated levels of cholesterol and triglyceride in the blood,
high blood pressure and
tobacco smoke.
Tobacco smoke greatly worsens and speeds up the growth of atherosclerosis in the coronary arteries , the aorta and arteries in the legs. (The coronary arteries bring blood to the heart muscle; the aorta is the large vessel that the heart pumps blood into to take to the body.) Because of the damage, over time fats, cholesterol, fibrin, platelets, cellular debris, calcium and other substances are deposited in the artery wall. These substances may stimulate the cells of the artery wall to produce still other substances that result in further accumulation of cells in the innermost layer of the artery wall where the atherosclerotic lesions form. These cells accumulate and many of them divide. At the same time, fat builds up within and around these cells. They also form connective tissue.
The innermost layer of the artery (the endothelium) becomes markedly thickened by these accumulating cells and surrounding material. If it's thickened enough, the diameter of the artery will be reduced and the blood flow decreased, thus reducing the oxygen supply. If the blood supply to the heart muscle is reduced, a heart attack can occur. If the blood supply to the brain is cut off, a stroke can occur. And if the blood supply to the arms and legs is reduced, gangrene can result.
Often a blood clot forms and blocks the artery, stopping the flow of blood.
