Cholesterol is a sterol (a combination steroid and alcohol) and a lipid found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. The name originates from the Greek chole- (bile) and stereos (solid), and the chemical suffix -ol for an alcohol, as researchers first identified cholesterol in solid form in gallstones in 1784. In the body, cholesterol can exist in either the free form or as an ester with a single fatty acid (of 10-20 carbons in length) covalently attached to the hydroxyl group at position 3 of the cholesterol ring. Because of the mechanism of synthesis plasma cholesterol esters tend to contain relatively high proportions of polyunsaturated fatty acids. Most of the cholesterol consumed as a dietary lipid exists as cholesterol esters. Cholesterol esters have a lower solubility in water than cholesterol and are more hydrophobic. They are hydrolyzed by pancreatic enzymes, cholesterol esterase, to produce cholesterol and free fatty ac

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