The circulatory system; the skin; human body review

The skin is the body’s biggest organ and its protective covering. It shields inner organs from knocks, drying out and germs. The skin has tiny pores through which oil and sweat come out. Oil keeps skin soft, and sweat evaporates and cools the body. Old skin cells on the surface keep falling off and new ones form; some of the dust in rooms comes from this, so wipe rooms with a damp cloth. The skin has many sensing points that feel pain, touch, heat and cold and send signals to the brain. Everyone’s fingerprints are different. Sunlight makes vitamin D under the skin, which bones need. But too long in the sun burns the skin. Skin colour depends on melanin, which gives some protection, but everyone — whatever their skin colour — should stay in the shade in strong sun, wear a hat and use sunscreen. For clean skin wash with soap and wash hands often.