Produced by hair follicles, consists of dead keratinized cells. 3 Layers of keratinized cells (medulla, cortex, cuticle)
Functions: Alerting the body to presence of insects on the skin, guards scalp against physical trauma, heat loss, and sunlight
Distribution: Entire surface except palms, soles, lips, nipples, and portions of external genitalia.
Contains hard keratin; more durable than soft keratin of skin
Hair pigments: melanins (yellow, rust brown, black)
Gray/white hair: decreased melanin production, increased air bubbles in shaft