Skin
Latin: Cutis
Location: Entire body surface
View the skin in 3DFunction
The skin is the body's largest organ — 1.5–2 square metres, 3.5–5 kg, and the boundary where biology meets the world. Its stratified epidermis replaces itself every 28 days, dead cells cemented into a brick wall of keratin and lipids that no microbe can penetrate unwounded.
Beneath, the dermis hosts the nervous system's outpost (touch, pain, temperature and vibration receptors), the circulation's radiator (blood flow varying 50-fold for temperature control), and 2–4 million sweat glands whose evaporation cools. The skin synthesises vitamin D in sunlight, blocks ultraviolet radiation with melanin and communicates emotion by blushing and paling. Its dendritic cells sample antigens as sentries of immunity.
Blood supply
Cutaneous vascular plexuses from perforating branches of underlying arteries — the dermis is among the body's richest perfused tissues for its mass.
Nerve supply
Segmental cutaneous nerves; sympathetic fibres drive sweat glands, vessels and piloerection.
Clinical relevance
- Melanoma
- Malignant melanocytes can metastasise early — the ABCDE checklist aims to catch it while it is still thin (Breslow <1 mm), when excision is usually curative.
- Burns
- Depth defines care: partial-thickness burns heal from appendageal stem cells; full-thickness loss needs grafting.
- Cellulitis
- Streptococci breach the barrier through a crack — spreading erythema tracked with a marker pen marks the response to antibiotics.
Related conditions
Educational anatomy reference, not medical advice. About this content.