Page 46 - 84 human physiolofy part-1
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Chapter 3
A hair follicle with associated structures.
The composition of sebum varies from species to species; in humans, the lipid content consists of
about 25% wax monoesters, 41% triglycerides, 16% free fatty acids, and 12% squalene.
The activity of the sebaceous glands increases during puberty because of heightened levels of
androgens.
Sebaceous glands are involved in skin problems such as acne and keratosis pilaris. A blocked
sebaceous gland can result in a sebaceous cyst. The prescription drug isotretinoin significantly reduces
the amount of sebum produced by the sebaceous glands, and is used to treat acne. The extreme use (up
to 10 times doctor prescribed amounts) of anabolic steroids by bodybuilders to prevent weight loss tend
to stimulate the sebaceous glands which can cause acne.
The sebaceous glands of a human fetus in utero secrete a substance called Vernix caseosa, a
"waxy" or "cheesy" white substance coating the skin of newborns.
The preputial glands of mice and rats are large modified sebaceous glands that produce
pheromones.
46 | Human Physiology
