Vellus Hair is a short, thin, little-colored, almost invisible hair that develops in most people's bodies during childhood. Exceptions include lips, the back of the ear, palms, soles of the feet, some external genital areas, navel, and scar tissue. Hair density - the number of hair follicles per area of ​​the skin - varies from person to person. Each strand of vellus hair is usually less than 2 mm (1/13 inch) long and the follicle is not connected to the sebaceous glands.
Vellus hair is most easily observed in children and adult women, as it generally has few terminal hairs to obscure it. Vellus's hair is not lanugo hair. Lanugo hair is a much thicker type of hair that usually grows only in the fetus.
Vellus hair is distinguished from the more visible terminal or androgenic hair, which develops only during and after puberty, usually to a greater extent in men than in women.
Latin uses the word vellus to designate "a fleece" or "wool". In the use of slang, vellus hair is sometimes referred to as "peach fuzz" because of its resemblance to the growing epidermis on the peaches.
Video Vellus hair
Development
Vellus hair replaces lanugo hair in a human fetus from the age of 36 to 40 weeks of pregnancy. The vellus hair growth cycle is different from the terminal hair growth cycle. At puberty, the androgen hormone causes many velvet hairs to become terminal hair and stimulates new hair growth in the armpit and pubic area. In men, this change in vellus hair occurs on the face and body.
Vellus hair grows individually or in small patches of varying sizes, and sometimes irregular, long (2-4 cm). This irregularity is governed by genetics, and often lasts throughout life. Growth of this kind of hair is usually not dangerous.
Maps Vellus hair
Function
Vellus hair provides thermal and cooling insulation for the body. This isolation regulates body temperature: the function of the hair vellus is like axis for sweat. While the skin pores open, sweat drenches a velvet hair. The sweat on the outside of the strands evaporated. More sweat moistens the outside of the vellus strand and then evaporates. This process is called sweat.
Clinical interests
Unusual hair growth vellus can be a side effect of some types of diseases. Abundance of vellus hair can develop from increased production of the hormone cortisol in a person with Cushing's syndrome. Anorexia nervosa increases vellus hair. Vellus hair can also be found in men with male pattern baldness or with hirsutism. Hormonal fluctuations in pregnant women cause fetal velus hair to turn into terminal hair. Terminal hair is usually released after the birth of the baby after the return of hormones to normal levels.
- Trichostasis spinulosa - A velvet hair located on the keratin sheath is diagnostic.
- Frontal fibrosing alopecia, a clinical variant of lichen planopilaris, is a female scarring alopecia characterized by a progressive recession of frontotemporal hairline. It is characterized by the absence of vellus hair in the hairline.
- Eruptive velupt hair cyst (EVHC), benign dermatological conditions in children and young adults.
Footnote
Source of the article : Wikipedia
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