Skin, nails, and hair All wrapped up Skin covers your whole body. It protects you from germs, water, and sunshine, and helps keep your body at the right temperature. The skin on your eyelids is the thinnest Two layers on your body. Your skin has two main layers. The top one – the one you can see – is called the epidermis. Underneath is the dermis, where there are nerves and blood vessels. Waterproof seal There are flat cells on the surface of your Skin stops water getting into your skin. These are made body when you have a shower or from a tough material go for a swim. It also stops fluids Sk called keratin. When the cells die, they dry out and escaping from inside you. in is flake off. a Magnified skin flakes sor Skin cells lower down t of replace the dead ones that flake off. s tre House dust tch Heavy load Dust is mostly on Skin is the made of dead y heaviest single skin. Dust mites overco n ski part of your feed on this skin. body. It can They live in st weigh as much beds, pillows, The thicke at. as a bag of and carpets. shopping. Dust mites aren’t really this big! They’re so small you can’t see them. 68 How many dead skin flakes fall off every day? All wrapped up Sweat Sweat pore Sweat gland If you uncurled a sweat gland, it could be over a metre (3ft) long. Skin colour The colour of your skin is affected by a substance called melanin. The more melanin you have, the darker you will be. When you are outside in the sun, your body produces extra melanin to protect your skin. This melanin makes your skin darker and you get a suntan. oles of y is on the s y r bod ou u yo r fe et. Cooling down When sweat dries on your skin, it helps to cool you down. Sweat comes from Soggy skin coiled tubes under the When you soak in water for a long surface. It gets out time, the top layer of your skin gets through tiny holes waterlogged and wrinkly. called pores. About ten million. 69
"All wrapped up (Skin, nails, and hair)"