Cholesterol Metabolism, LDL, HDL and other Lipoproteins

The science behind good and bad cholesterol. Cholesterol transport and pathways, drugs used for treatment of atherosclerosis.


Despite its unfavorable reputation as a cardiovascular disease risk factor, cholesterol is a necessary element in all animal cells. It is an integral component of the cell membrane that contributes to the fluidity of the membrane and several cellular functions. Additionally, cholesterol acts as a precursor in the synthesis of bile, steroid hormones, and vitamin D. However, many cells synthesize their own endogenous cholesterol, despite the fact that the body can also get cholesterol from meals.
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In the plasma, cholesterol and other lipids are carried by LIPOPROTEINS, which are substantial particles. An amalgamation of lipids and proteins called a lipoprotein. A lipoprotein’s DENSITY determines how it is categorised. Lipid particles are larger yet have a lower density than protein particles because lipids are LIGHTER than proteins. Distinct lipoprotein subtypes have different surface protein compositions. These proteins act as “ADDRESS tags,” identifying each lipoprotein’s DESTINATION and hence its FUNCTION. For instance, HIGH-density lipoprotein (HDL) RETURNS extra cholesterol TO the liver, whereas LDL transports cholesterol FROM the liver to other organs.