Integumentary System
The edge of youIntegumentum commune
Skin, hair, and nails — a self-repairing barrier that keeps water in, pathogens out, and reads the world by touch.
- Primary role
- Protects, senses, and regulates temperature
- Scale
- About 2 m², 3.5–5 kg
- Every day
- Sheds ~500 million cells
Organs in this atlas 1
How it works as a whole
Skin is the body's largest organ and its least appreciated one, doing at least six jobs at once: waterproofing, immune defence, temperature control, vitamin D synthesis, sensation, and repair. It manages this in three layers — a dead, constantly shed outer shield; a living dermis full of vessels, nerves, and glands; and a fatty base for insulation and padding. Its outermost cells are not alive, which is precisely the point: the barrier is built from its own casualties.
Other key structures
- Hair folliclesAnchor hair, host stem cells, and help repair wounds
- Sweat glandsCooling by evaporation — the body's main thermostat
- Sebaceous glandsOil that waterproofs skin and hair and holds bacteria in check
- NailsHardened keratin plates that stiffen the fingertip for grip
Connected systems
- Sensory SystemCarries touch, pressure, temperature, and pain receptors throughout
- Cardiovascular SystemDermal vessels shunt blood to shed or conserve heat
- Endocrine SystemStarts vitamin D synthesis, which the kidney later finishes
Common conditions
- Eczema
- Psoriasis
- Melanoma
- Cellulitis
- Burns
- Chronic wounds
The through-lineThermoregulation is a whole-body collaboration run through skin: vessels widen or clamp down to dump or hoard heat, sweat glands open, and hair muscles contract — all directed by the hypothalamus.
Did you knowFingerprints form in the womb from the way skin buckles as it grows, which is why identical twins do not share them.
The path through this system
0 of 10 steps done — read it, walk it in 3D, then be asked about it.
Start: Skin: the lesson
ReadSkin: the lessonStructure and story of the skin, layer by layer.
3 min
Guided walk-throughGuided dissection: skinWalk the skin structure by structure, then cut inward layer by layer.
6 min
Memo cardsSkin memo cardsTurn the cards on the skin — structures, layers, key facts — and grade yourself.
4 min
Multiple choiceSkin quizA multiple-choice round on the skin, reshuffled every time.
4 min
Click on the 3D modelFind the skin structuresClick the named structures directly on the live 3D skin.
5 min
Multiple choiceIntegumentary System quizA quiz pulling from every organ in the integumentary system.
3 minLabel the diagramLabelled diagram: SkinThe skin plate with its labels taken off: put each one back on its number, or draw it yourself first.
5 min
Match layersMatch skin layersPair each layer of the skin, outside in, with what it does.
4 min
Match pairsMatch skin structuresPair each structure in the skin with its role.
4 minReadSkin in the clinicWhere the skin shows up in the clinic, and what goes wrong.
3 min