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Hair is a protein filament that grows from follicles found in the dermis.Hair is one of the defining characteristics of mammals.The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair.
It is commonly stated that hair grows about 1 cm per month on average; however reality is more complex, since not all hair grows at once. Scalp hair was reported to grow between 0.6 cm and 3.36 cm per month. The growth rate of scalp hair somewhat depends on age (hair tends to grow more slowly with age), sex, and ethnicity. [3]
A variety of human hair colors; from top left, clockwise: black, brown, blonde, white, red. Human hair color is the pigmentation of human hair follicles and shafts due to two types of melanin: eumelanin and pheomelanin. Generally, the more melanin present, the darker the hair.
A strand of human hair has its own life cycle with four phases: anagen (the growth phase), which lasts several years; the transitional “catagen” period, which lasts a few weeks; telogen (the ...
The hair follicle is an organ found in mammalian skin. [1] It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions.. The hair follicle regulates hair growth via a complex interaction between hormones, neuropeptides, and immune cells
This measurement is not precise because human hair varies in diameter, ranging anywhere from 17 μm to 181 μm [millionths of a metre] [8] One nominal value often chosen is 75 micrometres (0.0030 in), [5] but this – like other measures based upon such highly variable natural objects, including the barleycorn [9] – is subject to a fair degree of imprecision.
Hair care or haircare is an overall term for hygiene and cosmetology involving the hair which grows from the human scalp, and to a lesser extent facial, pubic and other body hair. Hair care routines differ according to an individual's culture and the physical characteristics of one's hair.
While the role of estrogen, the primary female hormone, in human hair growth isn’t totally clear, it may play a protective role against hair loss in women. Estradiol, a form of estrogen, plays a ...