Hair growth in the adult regulated by the gonads. Male hormones cause hair growth on the face and body, but slow their growth on the head. Women's hormones act the opposite way, accelerating the growth of hair and slowing down on the body.Each hair on the body grows from follicle (hair follicles). They value each person genetically. The follicles represent the organs, inside which there are various chemical processes that cause hair growth. Such follicles on the human body about one million, but the body uses only 100-150 thousand.The speed of hair growth depends on the chemical processes occurring in the follicles. The more in the body of potassium, calcium, silicon, iodine, chromium, manganese, beta-carotene, Biotin, the active chemical processes occur and the faster growing hair, they will be strong and healthy. Deficiency in vitamins and minerals slows the growth of hair, they become dull and brittle.The speed of hair growth depends on the age of the person. Children grow at 13 mm per month, adults – 15 mm, the elderly – 11 mm. With proper selection of means to care the hair can grow 2 inches per month. Scientists have found that in the first half of the day, hair grow faster, and at night slow the growth or not grow at all.The number and growth of hair also depends on their color. True fact that blond hair in less than other people and red hair very thick. Therefore, proper care, appropriate type of hair is the key to their beauty, health and fast growth.Some women grow body hair of male type. Similar situations are observed in women with high levels of male sex hormones or taking hormones. But sometimes these events can be inherited or be a result of the excessive work of some enzymes in the hair follicles.