Acne is one of the more common and well-known skin diseases. There are sebaceous glands on the skin’s surface, which secrete an oily substance called sebum, whose job is to protect the skin. These glands can be found throughout the body, except for our palms and feet, but they are especially prevalent on the face and head.

These glands are usually located next to hair follicles and the sebum is secreted along the follicle and covers the hair and the skin in its surroundings. Hormonal changes in the body, especially a rise in testosterone during adolescence, cause a rapid replacement of skin cells around the hair follicle and a higher secretion of sebum. The combination of dead skin cells near the pores with a surplus of sebum may cause blockage in the gland and serve as a breeding ground for bacteria that occur naturally on the skin. The bacteria that accumulate in these areas can cause an infection which brings about a severe outbreak of acne.

The video shows the causes and various types of acne, and popular medical treatments.

 The video was translated by the Davidson Online team

Testosterone is considered a male hormone but is present in both sexes. Men make about 20 times more testosterone than women. The amount of the hormone in the blood system rises during adolescence in both males and females, which secrete it from either the testicles or the ovaries. Testosterone is vital for growth during adolescence and influences muscle mass, bone strength, body hair, changes in the voice, and other phenomena. After adolescence, the hormonal levels decrease and stabilize, but can change throughout the day.

Secretory glands can be divided into three groups, according to the type of secretion:

1. Merocrine secretion: Small vacuoles filled with the compound are secreted from the cell.

2. Apocrine secretion: A part of the membrane of the cell wraps around the secreted material and disconnects from the cell.

3. Holocrine secretion: The cell membrane is broken, the cell dies and everything inside spills out.

Sebaceous glands are the only holocrine glands in the body. This means the sebum secretion involves the death of the cells that secrete it. The normal role of these glands is to protect the skin and hair, to maintain skin moisture, and prevent it from drying. They are also a breeding ground for friendly bacteria that live in symbiosis on the skin and prevent harmful bacteria from invading through cracked and dry skin. Additionally, there is a special type of sebaceous glands on the eyelids that secrete a substance called meibum, which helps protect the eye and maintain the liquid layer around it. The oily substance prevents the tear layer that covers the eye from evaporating, and thus maintains the moisture inside.

Ido Kaminski

Department of Chemical Biology

Weizmann Institute of Science


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