1.1 how does the circulation work? (4)

1.1 bio.

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what is Atherosclerosis?

Atherosclerosis is the disease process that leads to coronary heart disease and strokes.

In Atherosclerosis fatty deposits can either block an artery directly or increase its chance of being blokced by a blood clot (thrombosis)

the blood supply can be completely blocked making cells permanently damaged.

In the arteries supplying the heart, this results in a heart attack ( myocardial infraction ) and in the arteries supplying the brain it results in a stroke.

The supply of blood to the brain is restricted or blocked, causing damage or death to cells in the brain.

narrowing of arteries to the legs can result in tissue death or gangrene.

An artery can burst where blood builds up behind an artery narrowed as a result of Atherosclerosis.

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what happens in Atherosclerosis?

1. the endothelium ( thin layer of cells lining the inside of the artery ) separating the blood that flows along the artery from the muscular wall, becomes damaged. e.g: it may be damaged from a high blood pressure putting to much strain on the layer of cells or toxis from cigarette smoke in the bloodstream.

2. Once the inner lining is damaged, there is an inflammatory response. White blood cells leave the blood vessel and move into the artery wall. These cells accumulate chemicals from the blood, particularly Cholestrol. a deposit builds up , called an atheroma.

3. Calcium salts and fibrous tissues also build up resulting in a hard swelling called and plaque on the inner wall of the artery. The fibrous tissue cause the alls to lose some of its elasticity.

4. Plaques cause the artery to become narrower. This makes it harder for blood to be pumped around the body and can lead to a rise in blood pressure. Now there is a dangerous positive feedback  building up. Plaques lead to a higher blood pressure meaning it is more likely that further plaques will form.

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