Cholesterol animation

Cholesterol is a lipidic, fat tissue found in the cell membranes and transported in the blood plasma of all animals. It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and fluidity. Cholesterol is the principal sterol synthesized by animals, but small quantities are synthesized in other eukaryotes, such as plants and fungi. It is almost completely absent among prokaryotes, which include bacteria. Cholesterol is classified as a sterol (a contraction of steroid and alcohol).

Although cholesterol is essential for life, high levels in circulation are associated with atherosclerosis. Cholesterol can be ingested in the diet, recycled within the body through reabsorption of bile in the digestive tract, and produced de novo. For a person of about 150 pounds (68 kg), typical total body cholesterol content is about 35 g, typical daily dietary intake is 200–300 mg in the United States and societies with similar dietary patterns and 1 g per day is synthesized de novo.

The name cholesterol originates from the Greek chole- (bile) and stereos (solid), and the chemical suffix -ol for an alcohol, as François Poulletier de la Salle first identified cholesterol in solid form in gallstones, in 1769. However, it was only in 1815 that chemist Eugène Chevreul named the compound "cholesterine".


Cholesterol is required to build and maintain cell membranes; it regulates membrane fluidity over the range of physiological temperatures. The hydroxyl group on cholesterol interacts with the polar head groups of the membrane phospholipids and sphingolipids, while the bulky steroid and the hydrocarbon chain are embedded in the membrane, alongside the nonpolar fatty acid chain of the other lipids. In this structural role, cholesterol reduces the permeability of the plasma membrane to protons (positive hydrogen ions) and sodium ions.

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