Cholesterol is insoluble in blood plasma so it is transported by lipoproteins,which are made intheliver.
The centre of a liporprotein contains cholesterol and other lipids (triglycerides and steroids). They are coated in a singlephospholipidlayer, with proteins to make it soluble.
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High Density Lipoproteins
More proteins, fewer lipids
Removecholesterolfromtissuesand return it to theliver
HDL receptorsonliver cells
Decrease blood cholesterol and fat deposists
Decrease rate of formation of atheromas (plaques)
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Low Density Lipoproteins
More lipids, fewer proteins
Deliver cholesterol to tissues from the liver
LDL receptors on tissue cells
Raise blood cholesterol and fat deposits
Increase rate of formation of atheromas (plaques)
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First Step
If the endothelial lining of an artery is damaged,LDLs tend todepositfatand cholesterol in them.
This accumulates along with fatty acids, calcium salts and fibrous tissues, forming an atheromatous plaque.
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Second Step
Atherosclerosis is the stiffening and hardening of the artery walls caused by a build-up of plaque.
This leads to a bulge in the artery wall which narrows the lumen and restricts blood flow.
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Third Step
If oxygenated blood flow is restricted, thecardiacmuscle may become deprived of oxygen and fatigued, causinganginawhich is severechest pains.
The plaque deposits also roughen the lining of the artery which increases the risk of blood clots forming.
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Fourth Step
If the artery is almost completely blocked by atheromatous plaque and blood clots, a heart attack (myocardial infarction) may occur.
Cardiac muscle is starvedofoxygen and cells rapidly die. This may befatal.
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