Definition of Lipoprotein
Lipoprotein: A complex of lipid and protein, the way
lipids travel in the blood.
Cholesterol, a building block of the outer layer of cells (cell
membranes), is transported through the blood in the form of water-
soluble carrier molecules known as lipoproteins. The lipoprotein
particle is composed of an outer shell of phospholipid, which renders
the particle soluble in water; a core of fats called lipid,
including cholesterol and a surface apoprotein molecule that allows
tissues to recognize and take up the particle. These lipoproteins are
characterized by their density: high density lipoprotein (HDL), low
density lipoprotein (LDL), very low density lipoprotein (VLDL).
The first stages of cholesterol build up in the blood vessels
(atherosclerosis) occur when LDL particles circulating in the blood
penetrate through the inner lining of blood vessels and become
trapped in the artery wall. Eventual build up of LDL, fat-filled
cells, cells of inflammation, and blood clotting can block the normal
blood flow in the coronary arteries. This is a catastrophic event
that stops the flow of nutrients and oxygen to the heart muscle,
leading to heart attack (myocardial infarction).
Last Editorial Review: 12/4/2000
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