The normal growth of hair
Hair is composed of two parts: the stem and root. The stem is made of keratin, a protein also entering into the composition of the nails and built in the deep part of the skin. The root, bulbous, sinks into the skin and allows the membership of the hair to the scalp. A pilosebaceous follicle, sebaceous gland comprising (which produces sebum) and pilo-arrector muscle (which establish the hair on the head in case of strong emotion!) Is attached to the hair.
Hair has an average 100,000 to 150,000 hair, with a density of 250 to 300 hairs per square centimeter. The hair grows normally 1 cm per month and its lifetime varies from 2 to 6 years.
It is normal to lose 25-100 hairs a day. In the same person, there are hair growth phase and other phase of fall: this is explained by the existence of a hair cycle consisting of three periods. The longest phase is the "anagen" or growing phase of the hair, which lasts about three years. The next phase "catagen" or resting phase, very short (2 to 3 weeks). The cycle ends with the phase "telogen" phase or fall, about three months.
All the hair does not lie at the same stage at the same time: more than 75% of hair is in growth phase, 1% are in the resting phase and less than 25% fall in line. Hair growth is usually subject to various influences, like the seasons, genetic factors, hormonal factors (which are male hormones or androgens, which are relevant here). Finally, as the whole body, the hair is aging: the hair cycles are shortening and after 50 years, the hair grows more slowly.
Hair loss (or alopecia) on all or only part of the scalp, may be related to many causes: hormonal, drug, disease or physical or chemical.
Hair has an average 100,000 to 150,000 hair, with a density of 250 to 300 hairs per square centimeter. The hair grows normally 1 cm per month and its lifetime varies from 2 to 6 years.
It is normal to lose 25-100 hairs a day. In the same person, there are hair growth phase and other phase of fall: this is explained by the existence of a hair cycle consisting of three periods. The longest phase is the "anagen" or growing phase of the hair, which lasts about three years. The next phase "catagen" or resting phase, very short (2 to 3 weeks). The cycle ends with the phase "telogen" phase or fall, about three months.
All the hair does not lie at the same stage at the same time: more than 75% of hair is in growth phase, 1% are in the resting phase and less than 25% fall in line. Hair growth is usually subject to various influences, like the seasons, genetic factors, hormonal factors (which are male hormones or androgens, which are relevant here). Finally, as the whole body, the hair is aging: the hair cycles are shortening and after 50 years, the hair grows more slowly.
Hair loss (or alopecia) on all or only part of the scalp, may be related to many causes: hormonal, drug, disease or physical or chemical.
Category Article Hair Growth
