Essentially created of keratin, hair likewise contains other elements and also molecules that add to the appearance and also behaviour
The in its entirety chemical ingredient of hair is 45 % carbon, 28 % oxygen, 15 % nitrogen, 7 % hydrogen and 5 % sulphur.
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The hair pillar is essentially composed of keratin. Hair keratin is hard, compact and also strong. This fibrous protein is gradually developed inside cell from the germinal layer. These cuticle cells are qualified by the visibility of amorphous keratin while the cortical cells have actually a structure of filaments surrounded by a keratinic substance the is richer in sulphur and also contains amino acids. The keratin of these filaments forms a helix, with a distance in between the turns of 0.51 nanometres and also a structure preserved by hydrogen bonds. This protein plays a vital role in the cohesion and also physical properties of hair.
Hair also contains water (12 to 15 %) and also traces that mineral facets (calcium, cadmium, chromium, copper, zinc, iron and silicon). These elements can be lugged to the base of the hair follicle by blood circulation and also then add to structure the hair shaft. As well as this contribution, the environment can, for instance through pollution, it is in the source of details elements such together lead.
The hair likewise contains lipid contents (3% that its composition). They are developed in the hair bulb from sterols, fat acids and also ceramides. Existing essentially in the intercellular cement the the cortex and also the cuticle, they provide the hair through a particular impermeability and ensure the cohesion that the hair fibre.
Other lipids come from the cheap of the sebaceous gland: sebum. Sebum is developed from tires sebaceous cell which have burst open and it mainly has lipids (triglycerides, waxes, squalene, esterified cholesterol and free cholesterol). The most abundant triglycerides experience partial hydrolysis by the bacteria the inhabit the scalp, Propionibacterium acnes and Propionibacterium granulosum. This hydrolysis liberates free fatty acids, di- and monoglycerides and also glycerol. The fatty acids are qualified by carbon chains, even and also uneven in number (from C11 come C19), with countless unsaturated sections and also branches. The waxes room esters that acids and also long-chain alcohols. The waxes room apolar compounds which room metabolised through the flora and also are little affected by oxidation.
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In the sebaceous gland, acetate molecules condense to form mevalonic acid, one isoprenoid isomer and also squalene, a direct hydrocarbon created from 30 carbon atoms. The sterols space esterified through the fatty acids. The squalene/cholesterol ratio in the surface ar hydrolipidic movie is a mirror of the biological tasks of the sebaceous glands and the epidermis. The lipid mixture which forms this film on the surface of the skin lubricates the hair and thus preservation the suppleness and shine of the hair. Being hormone dependent, the sebum can be produced in excess and also the hair becomes greasy and also heavy. On the various other hand, if too little is secreted, the hair becomes dry, dull and damaged.
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