Skin, Hair and Nails

Your skin is your body's biggest organ. It covers every centimetre of you and does a remarkable number of jobs: it keeps water in, keeps germs out, protects you from sunlight, helps control your temperature, and lets you feel the world around you.

Think of your skin as a brilliant waterproof coat that you never take off. It stops your insides from drying out and forms a barrier that blocks most germs before they can get in. It even repairs itself when you get a scratch, growing brand new skin to seal the gap.

Beneath the epidermis is the dermis, which is packed with sweat glands, oil glands, blood vessels, and nerve endings. Deeper still is the hypodermis — a layer of fat that helps insulate you, keep you warm, and cushion knocks and bumps.

Your skin is a clever thermostat that keeps your body at just the right temperature. On a hot day you sweat: the water on your skin evaporates and takes heat away with it, cooling you down. When you are cold, tiny muscles pull your hairs upright to trap warm air, giving you goosebumps.

Hair grows from tiny pockets in the dermis called follicles. Each strand is made of a tough protein called keratin — the very same protein that makes your nails. Hair helps keep you warm and protects your skin, and your eyelashes and eyebrows keep dust out of your eyes.

Your nails are hard shields that protect the sensitive tips of your fingers and toes, and they help you pick up tiny objects and scratch an itch. The pink part you see has living cells growing underneath, which is why trimming the white tip never hurts.