Keratin Keratin Keratin () is one of a family of fibrous structural proteins. It is the key structural material making up hair, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin derives from Greek ' from '
Hair for causing hairs to stand up. In humans with little body hair, the effect results in goose bumps. The "root of the hair" ends in an enlargement, the "hair bulb", which is whiter in color and softer in texture than the shaft, and is lodged in a follicular involution of the epidermis called the hair follicle. Bulb of hair layers consist of fibrous connective tissue, glassy membrane, external root sheath, internal root sheath composed of epithelium stratum (Henle's layer) and granular stratum (Huxley's layer), cuticle, cortex and medulla of hair. All natural hair colors are the result of two types