The body’s largest organ is the skin. It is like a thin, protective coat that covers the whole of your body. Tough, stretchy and waterproof, skin protects the body from damage and keeps germs out. It stops you getting either too hot or too cold and blocks harmful rays in sunlight. The skin also contains millions of tiny nerve endings. These provide the body’s sense of touch.

Epidermis

Your outer layer of skin is called the epidermis. It is always replacing itself as the dead skin flakes are worn away. Melanin, a brown pigment, gives your skin its colour. It filters out harmful rays in sunlight. If you spend a lot of time in the sun, the skin makes more melanin, so it becomes darker. Dark-skinned people have more melanin in their skin than light-skinned people.

Sweat

There are millions of microscopic sweat glands in the dermis. When it is hot, sweat, a salty liquid, is released by these glands. Droplets of sweat, or perspiration, appear on the skin. The sweat takes heat away from your skin as it evaporates. This helps cool the body.

Sensors

The dermis contains nerve endings, or sensors. These detect touch, heat, cold and pain. They send signals along nerves to your brain. Some parts of the skin are more sensitive than others. This is because they have more sensors than other parts. They include the lips, fingertips and the soles of your feet.