Human hairs. Coloured scanning electron micrograph (SEM) of a shaft of hair from a human head. The outer layer of a hair shaft (the cuticle) has overlapping scales of keratin. The scales are thought to be important in preventing matting of the hair. Hair is made up of the protein keratin, which is provided by the living root embedded in the skin. Hair grows from this root. As the bulb produces more keratin, a hair shaft forms and is pushed outwards from the skin.