Hair are appendages of skin and cover practically all surface of human body. There are only two sites where they do not grow - it is palms of hands and sole of legs.
Growth of hair at the adult is regulated by work of gonads. Male sex hormones cause growth of hair in the face and body, but at the same time slow down their growth on the head. Women's hormones work with opposite obkraz, accelerating growth of hair on the head and slowing down on body. Each body hair grows from follicle (hair bulb). Their size at each person is put genetically. Follicles represent bodies in which there are various chemical processes causing growth of hair. Such bulbs on human body about one million, but the organism uses only 100-150 thousand. Growth rate of hair depends on the chemical processes happening in follicles. The more in organism of potassium, calcium, silicon, iodine, chrome, manganese, beta carotene, biotin, the more actively there are chemical processes and the quicker hair grow, at the same time they will be strong and healthy. The lack of organism of vitamins and minerals slows down growth of hair, they become dim and fragile. Growth rate of hair depends also on age of the person. At children the hair grow by 13 mm a month, at adults – on 15 mm, at elderly – on 11 mm. At the correct selection of care products the hair can grow on 2 centimeters a month. Scientists have established that hair grow in the first half of day quicker, and slow down growth at night or do not grow in general. The quantity and growth of hair depends also on their color. Established fact that blondes have hair less, than at other people, and red hair the most dense. Therefore the correct leaving corresponding to type of hair is the key to their beauty, health and rapid growth. At some women the body hair grow on men's type. Similar situations are observed at the women having the high level of male sex hormones or taking the hormonal drugs. But the similar phenomena can sometimes be descended or be result of excessive work of some enzymes of hair bulb.