A normal healthy person has approximately 2 g cholesterol per liter plasma. Figure 1 . The LDL is a spherical particle with a radius of one millionth millimeter. Most of the cholesterol in the blood stream is found in LDL particles. Its core consists of approximately 1,500 cholesteryl esters, each a cholesterol molecule attached by an ester linkage to a long fatty acid chain.
Cholesterol has two main functions in the body.
It constitutes a structural component in cell membranes, and it is converted to certain steroid hormones and bile salts. More than 90 per cent of the cholesterol in the body is found in cell membranes. Each cell is surrounded by a membrane, the cell or plasma membrane. Its function is not only to be a protective coat. It also serves as a border control determining which substances are allowed to enter or leave the cell.