Hair, nails and skin glands all grow from the epidermis down into the dermis. They protect the body, help control temperature and give useful clues during an exam.
Hair
Each hair grows from a follicle with living cells at its base and is made of dead keratin above the skin. A small muscle attached to the follicle pulls the hair upright in cold or fear, causing goosebumps.
Nails
Nails are hard plates of keratin that grow from the nail matrix under the cuticle. The pink nail bed underneath shows the blood flow just below the surface.
Sweat glands
Eccrine glands cover most of the body and release watery sweat that cools the skin as it evaporates. Apocrine glands in the armpits and groin start working at puberty and their sweat causes body odor when bacteria break it down.
Oil glands
Sebaceous glands open into hair follicles and release sebum, an oil that keeps skin and hair soft and waterproof. Blocked glands are the start of acne.
At the bedside
Press a nail bed to check capillary refill, normally under 2 seconds. Look at nails for clubbing or a blue tint, and remove dark nail polish or use another site if a pulse oximeter reads poorly.
Related guides
Written by Making Synapses. Topic reference: OpenStax, Anatomy and Physiology 2e (no text adapted).