The human hair
An important feature of mammals is that they are all covered with hair. The human, or the sapien, belongs with the mammal group; humans have various kinds of hair:
Hair covers the entire body, with the exception of soles of feet, palms of hands, mucous membranes, and lips.
25% of all hair is hair on the head. A human hair on the head (we can call him "Hairy") has 90,000 to 140,000 brothers and sisters.
Hairy: the human hair on the head
Hairy grows 0.25 to 0.40 millimeters per day.
This means an average growth as follows:
Every day, Hairy loses up to 100 brothers and sisters.
Hairy and his hairy siblings grow daily by a total of 30 meters.
Hairy: under the microscope
Hairy: the hair is built in a tubular way and consists primarily of a substance called keratin. Hairy is absorbant like a sponge. The contents of the tubular hair determines his color. The surface of the tubular structure is scale-like, covered with tiny plates. Hairy does not contain nerves or blood, but instead is rooted in living skin, which is how a uniform structure is formed.
The hair is divided into a shaft: the portion growing above the skin and the hair roots anchored in the skin.
The hair root of an individual hair forms a tiny but long tunnel (called a follicle) which reaches into the lower layers of the skin. At the end of the tiny tunnel, there is a hair papilla. The papilla is the center of growth for the hair; it is where nutrients are taken up from the blood.
Slightly below the surface of the skin there are sebaceous glands which supply the hair with sufficient sebum, the fatty secretion of these glands. A tiny hair-raising muscle is responsible for providing sebum from the sebaceous glands. This tiny muscle can also make the hair stand up straight when a person has goose bumps.
The lifespan of Hairy is three to seven years on average.
Hairy: his three phases of life
The growth phase: Hairy sits firmly in the hair papilla and, dependent upon genetic factors, matures during his 2 to 7 years in the growth phase.
The transitory phase: In the transitory phase of approximately 2 to 4 weeks, Hairy turns himself loose from the papilla and moves slowly upward in the hair follicle.
The resting phase: After a resting phase of 2 to 4 months, Hairy has reached the sebaceous gland and is ready to fall out, thus making room for his successor.
Hairy: his menu plan
Especially healthy for Hairy and for other hair are wholemeal products, eggs, liver, kidneys, vitamin D, herrings, salmon, carrots, green vegetables, and vitamin C.
The pigments give Hairy his color. When the human being upon whom Hairy lives turns old, then Hairy receives fewer pigments and the hair turns gray or white.
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