Acne is one of the most known and common skin conditions. At the surface of the skin there are glands named “sebaceous glands” that secrete an oily substance called sebum. The purpose of sebum is to protect the skin. These glands exist all around the surface of the body apart from the palms of the hands and the soles of the feet, but they are most densely found in the face and head.

Usually, these glands are adjacent to hair follicles, and the sebum is secreted along the follicle, coating the hair and the skin around it. Hormonal changes in the body, and especially the rise in testosterone levels during adolescence, causes rapid turnover of skin cells around the hair follicle and an increased secretion of sebum. The combination of dead skin cells around the pore and the increased sebum secretion could lead to obstruction of the gland. This obstruction could lead to favorable growth conditions for bacteria that naturally reside on the skin. When these bacteria grow around these areas, this could lead to inflammation, which in turn leads to a severe acne outbreak.

The following video presents the causes of acne, different possible symptoms, and common medical treatments.

The video was translated by the Davidson Online team

Testosterone is considered the male hormone; however, it exists in both sexes. In humans, men create roughly 20 times more testosterone than women. The amount of the hormone in the bloodstream rises during adolescence in both sexes, secreted from the testes and ovaries respectively. Testosterone is vital for the growth during adolescence and affects muscle mass, bone density, hairiness, vocal changes and many more. After adolescence, the hormonal levels of the body decrease and stabilize further, but still fluctuate periodically throughout the day.     

Secretion glands throughout the body can be classified into three types, based on the method of secretion:

1. Merocrine secretion: where tiny vesicles containing the substance are secreted from the cell.

2. Apocrine secretion: where the top of the cell detaches (the cell membrane is “pinched”) and then breaks down to particles containing the vesicles with the secreted substance.

3. Holocrine secretion: where the cell membrane ruptures, the cell dies and its content is poured out.

Sebaceous glands are the only kind of holocrine glands in the body, meaning that the secretion of sebum involves the death of the cells secreting it. The normal function of these glands is to protect the skin and hair, maintain moisture level and prevent dehydration. In addition, it provides good conditions for friendly bacteria that live in symbiosis on the surface of the skin and prevent the invasion of harmful bacteria that can penetrate dry and cracked skin. There is also a special type of sebaceous glands on top of the eyelids (called Meibomian glands). Meibomian glands secrete an oily substance called meibum which protects the eye and maintains a liquid environment around it. The oily substance prevents the layer of tears covering the eye from evaporating and protects the eye’s humidity.


Ido Kaminsky
Department of Chemical Biology
Weizmann Institute of Science


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