Sebaceous glands, as already mentioned, are closely connected with the hair, representing an important derived skin. Animal human ancestors, like modern apes, hair densely covered body. The modern man is gradually dying appendages of the skin. Known value hair maintain friction in places where that is why they are more developed, and on the head. The number of hairs on the human head ranges from 80 thousand (in red) to 140 thousand (blond). If tiny vellus hair covering the body, I live just up to 50 days, long hair on your head can live for several years, growing on 11-12 mm per month. So, for 10 years, they could grow by 1.5 meters. However, so long hair live only in rare cases. On average, long hair on his head live for about 3 years. It is easy to calculate that every day should be replaced about 100 hairs. Not knowing this, we often complain of excessive hair loss. Meanwhile, each day they shall die, and thus fall out of 100 pieces. Dead hair loss is not immediately; on the head sometimes up to 1/4 of the dead hair. It is clear, therefore, that the faster we combed hair, the more it seems to us that they have "the climb".
The hair roots are in addition to the sebaceous glands and muscle fibers, which are controlled by the sympathetic nerve. When he gets excited when anger, terror, etc., - the muscles tense make your hair stand on end. When we are cold, these muscles are responsible for the emergence of the so-called goose skin.