Steroids are a type of lipid characterized by a seventeen carbon atom fused ring structure. This structure has four interconnected rings and a variety of functional groups attached depending on the class of steroid. Steroids are found throughout the human body and produce significant effects even in small amounts. There are four different classes of steroids including cholesterol, bile acids, adrenocorticoid hormones and sex hormones. While each of these types of steroids have similar structures, they have vast differences in their effects.

Cholesterol is one of the most abundant and important type of steroid and is found in nearly every organism known. It is located in all cells and in both brain and nervous tissue where it helps form myelin tissue. It has the typical steroid ring structure, but also contains a hydroxyl group which creates some unique functional characteristics. One implication of this hydroxyl group is that...