Skin, hair, and nails are made of similar types of cells. They form the outer layer of the body, called the integumentary (in-teh-gyoo-MEN-tah-ree) system. It protects everything inside the body.

What Do Skin, Hair, and Nails Do?

Skin, hair, and nails do many jobs. They:

• Block germs and dirt from getting inside the body and causing harm.
• Protect the inside of the body from injury.
• Help control body temperature.
• Prevent water that's inside the body from evaporating.
• Stop water from getting absorbed when we bathe or swim.

How Do Skin, Hair, and Nails Help Other Body Systems?

Other body systems rely on skin, hair, and nails to help them do their jobs:

• Skin and nails block germs from getting inside the body, which helps the immune system.
• Hairs in the nose help the respiratory system by catching tiny particles and keeping them out of the lungs.
• Skin helps the endocrine system by absorbing vitamin D from the sun, which helps the body use calcium. Calcium is needed for strong bones.
• Skin holds nerve endings that let us feel hot and cold, touch, and pain. This helps the nervous system respond to what’s happening inside and outside the body.