Hair covers the entire body, with the exception of soles of feet, palms of hands, and lips. 25% of all hair is hair on the head. A Human has approximately 90,000 to 140,000 hairs on the head. Hair grows 0.25 to 0.40 millimetres per day.
This means an aJleragegrowth as follows:
• 1 hour = 0.0125mm
• 1 day = 0.3 mm
• 1 week = 2.1 mm
• 1 month = 1cm
• 1 year = 12cm
Everyday the average head loses up to 100 hairs a day. The hair is built in a tubular way and consists primarily of a substance called keratin. Hair is composed primarily of proteins (88%) "Keratin". Human hair is only about 2mm thick. Hair is absorbent like a sponge.
The contents of the tubular hair determines the colour. The hair surface structure is scale-like, covered with tiny plates. It does not have nerves or blood, but instead is rooted in living skin, whlch is how a uniform structure is formed.
Slightly below the surface of the skin there are sebaceous glands which supply the hair with sufficient sebum, the fatty secretion of these glands. The lifespan of a Hair is Three to Seven years on average.
There are three phases to hair life.
• Growth phase: It sits firmly in the hair papilla and, dependent upon genetic factors, matures during the 2 to 7 years in the growth phase.
• Transitory phase: approximately 2 to 4 weeks, it comes out from the papilla and moves slowly upward in the hair follicle.
• Resting phase: after resting phase of 2 to 4 months, it reaches the sebaceous gland and is ready to fall out, thus making room for the next hair.
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