A nitrogenous substance, or mixture of substances, containing sulphur in a loose state of combination, and forming the chemical basis of epidermal tissues, such as horn, hair, feathers, and the like
It is an insoluble substance, and, unlike elastin, is not dissolved even by gastric or pancreatic juice
a fibrous scleroprotein that occurs in the outer layer of the skin and in horny tissues such as hair feathers nails and hooves
this strong protein is found in skin, hair, and nails It acts as a structural protein and also provides protection Dry skin tends to have more keratin than other skin types