The Skin Suit
Your largest organ â wrapped all around you
Your largest organ isn't inside you â it's wrapped all around you. Your skin! About two square metres of living suit that waterproofs you, senses the world, and repairs itself.
A cross-section of skin
Real anatomy picture coming soon
Real anatomy photo spot: skin layers â epidermis, dermis and hypodermis
Three layers deep
Your skin has three layers. On top, the epidermis â a thin, tough, waterproof shell that you shed and replace completely about every 28 days. Beneath it, the dermis â packed with touch sensors, sweat glands, and blood vessels. Deepest, the hypodermis â a cushion of fat that insulates you and absorbs bumps.
The living suit
Skin does an astonishing list of jobs: it keeps water in and germs out, makes vitamin D from sunshine, cools you with sweat (Lesson 43), and reports touch, pressure, heat and pain to your brain (Lesson 39). It even heals itself when cut â sealing the hole with a scab that you're not supposed to pick at!
Mr. Bones says: I'm a fictional skeleton, not a doctor! This is for learning and fun. If anything hurts, stop and tell a grown-up you trust.
