Hair structure,😯😯

The hair is made up of 95% keratin, a fibrous, helicoidal protein (shaped like a helix) that forms part of the skin and all its appendages (body hair, nails, etc.). Keratin is synthesized by keratinocytes and is insoluble in water, thus ensuring impermeability and protection for the hair. Some 18 amino acids can be found in the hair, such as proline, threonine, leucine and arginine. Keratin is particularly rich in cysteine (a type of sulfurated amino acid), which forms disulfide bonds between molecules, adding rigidity and resistance to the entire structure The hair’s structure can be divided into 3 distinct parts: - Medulla: innermost layer of the hair shaft, composed of an amorphous, soft, oily substance - Cuticle: thin protective outer layer that contains the nourishing portion essential to hair growth. It is highly keratinized, composed of cells shaped like scales that are layered one over the other, measuring about 60 micrometers long and about 6 micrometers wide. - Cortex: main component of the hair, containing long keratin chains that add elasticity, suppleness and resistance to the hair. The cells of the cortex are joined together by an intercellular cement rich in lipids and proteins. Each cell is composed of bundles that lie in the direction of the hair length: these are macrofibrils which are made up of microfibrils, which in turn contain protofibrils.