The fourth main function of cholesterol is neurological. Cholesterol is "an important part of the myelin sheath which is a neuron consists of fat-containing cells that insulate the axon from electrical activity," (Miezam, n.d.). Fifth, cholesterol aids the body's natural immune defenses.

One of the features of cholesterol is, as a waxy substance, it cannot dissolve in blood. Cholesterol moves through the bloodstream, and are carried through it by lipoproteins. When the cholesterol is derived from food, the molecules are transported from the intestine to the liver by the lipoprotein molecules. At that point, the liver processes the cholesterol into Very Low Density Lipoprotein (VLDL), which contains "cholesterol and cholesterol ester among other compounds" and releases VLDL into the blood ("Cholesterol" n.d.). The VLDL may then be stored in fat tissue in the body. Stored in the fat tissue, the VLDL is partially converted into Low Density Lipoprotein (LDL), which is the transport protein for cholesterol. Too much LDL will "slowly build up in the walls of the arteries feeding the...

However, one-third to one-fourth of the body's cholesterol is carried by high-density lipoprotein (HDL), which carries cholesterol "away from the arteries and back to the liver, where it's passed from the body," (American Heart Association, 2010, "Cholesterol"). For this reason, HDL lipoprotein is commonly referred to as "good cholesterol."