| A | B |
|---|
| hair root | part of the hair located below the surface of the scalp |
| hair shaft | portion of the hair that projects above the skin |
| follicle | tube-like depression in the skin or scalp that contains the hair root |
| hair bulb | lowest part of the hair strand; club-shaped structure that forms the lower part of the hair root |
| dermal papilla | small, cone-shaped elevation at the base of the hair follicle that fits into the hair bulb; contains blood and nerve supply that provides nutrients for hair growth |
| arrector pili | minute, involuntary muscle fiber in the skin inserted in the base of the hair follicle; when it contracts, the result is "goose bumps" |
| sebaceous glands | oil glands of the skin; connected to hair follicles; secrete sebum which lubricates hair and skin |
| cuticle | outermost layer of hair; consists of overlapping scale-like cells; primary defense against damage to hair |
| cortex | middle layer of hair; 90% of hair weight; elasticity and hair's natural color result from protein structures |
| medulla | innermost layer; called pith; generally, only thick, coarse hair contains a medulla |
| trichology | scientific study of hair, its diseases, and care |
