Site pages
Current course
Participants
General
Topic 1
Topic 2
Topic 3
Topic 4
Topic 5
Topic 6
Topic 7
Topic 8
Topic 9
Topic 10
Topic 11
Topic 12
Topic 13
Topic 14
Topic 15
Topic 16
Topic 17
Topic 18
Topic 19
Topic 20
Topic 21
Topic 22
Topic 23
Topic 24
Topic 25
Topic 26
Topic 27
6.2.1.2.2.4 Steroids
The steroids are found in association with fat. All of the steroids have a similar cyclic nucleus resembling phenanthrene (rings A, B and C) to which a cyclopentane ring (D) is attached. The parent substance is cyclopentano-perhydrophenanthrene.
Steroid nucleus (cyclopentano-perhydrophenanthrene) Steroids play many physiologically important roles. Cholesterol is probably the best known steroid. It is of significance because it is the precursor of a large number of equally important steroids which include the bile acids, adrenocortical hormones, sex hormones, D vitamins, cardiac glycosides, sitosterols of the plant kingdom, and some alkaloids. Cholesterol is found is cell membrane, nerve, brain tissue, and in all fluids. Ergosterol is a plant steroid used for the synthesis of vitamin D.
Cholesterol |