Structure and function of the hair

The amount of hair varies between some 85,000 with red headed and 150,000 with blonds, representing 300 to 900 hairs per square centimeter.

On average a hair is 0.08 mm thick and grows between 0.1 and 0.2 mm per day. Hair consists of formed horn threads build from specialized skin cells. These are mainly built from keratin with embedded lipids that give the hair its elasticity. Melanin gives color.

The inner center of thick hair contains of hair mark that is missing in thin hair. Then comes the fiber layer or so-called cortex which is covered by the barn layer. i.e. cuticula. Here, small single dandruff, i.e. dead skin cells, is stored in a roof brick pattern, one above the other.

The hair root manages the growth of hair. It is situated in the dermis, is nourished by a dense network of fine blood vessels in the dermal papilla and is permanently forming new hair material out of specialized skin cells of the hair matrix. The hair root is surrounded by an internal and external root line. In the upper area of the leather skin the hair muscle verges onto the so called follicle material where the tallow glands discharge. Tallow represents an additional protection of the hair surface.

Pigment cells, so called melanocytes, which are situated in the hair root produce brown-black (eumelanin) or reddish-yellow colorants in a quantity determined by genetic endowment. These colorants determine the hair’s color. With increasing age less colorant is produced making hair grey.

The hair’s natural form is also genetically determined. The rounder the hair’s cross-section, the smoother the hair; the more prolate, the curlier.

The growth of hair is subject to a regular cycle. With its two to six weeks, the time of continuous growth, also known as anagen phase, represents the longest phase in the cycle. This phase is followed by two weeks of transition, also known as catagen phase, where the hair root disappears, stops growing and is finally also falling out. The subsequent quiet phase, telogen phase, lasts about three to four months. At the end of this phase a new hair root is formed from stem cells. This hair then begins a new hair cycle, again starting with the telogen phase.