Integumentary System

The integumentary system makes up the body’s skin, nails, and hair. Each of these parts of the body plays an important role.


The skin helps to protect the body from infection and repels water. The skin has an outer layer called the epidermis and the cells are formed in the first layer and move up and new cells form below.

When this happens, the skin dies and falls off. A human loses many skin cells each day. The dermis is the inner layer and the tissue is strong and elastic.

There are many blood vessels in the dermis and there is a fat layer that protects the body from high and low temperatures.

Functions of the Skin

The skin contains sweat and oil glands that help rid toxins out of the body. The skin can heal itself. If the skin is burned, depending on the burn, the skin can heal.

First degree burns hurt but they heal fast while the second- and third-degree burns can cause death.

Hair and Nails

Hair and nails play an important role in the body. The hair helps to protect the body from the sun and it also traps in heat when it is cold outside.

The hair has different parts such as the cuticle, the cortex, medulla, external roots, internal roots, and matrix which is the tissue that helps to keep the hair in place.


Hair grows when there are new cells that form in the skin and the cells are replaced by new cells. Hair also protects your ears and is made of a protein substance that is called keratin. Hair is only found in mammals and it is dead, keratin that is filled with cells that overlap each other.

Hair protects the body from heat loss and eyelashes and eyebrows protect the eyes from dirt and water and other irritants that flow in the air. Hairs in the nose trap particles so that they do not reach the lungs.


The nails help to protect the fingers and toes from different types of injuries. The nails are made of epidermal cells that are thick and strong.

The nails have sensory receptors under them and this helps to tell the body when it is cold if there is pressure or pain and they help protect the body.

Nails help to keep the fingers from bending backward. Nails, just like hair are made of keratin and the keratin helps to make the nails hard.

What Did You Learn?

  • What does the skin do? The skin protects the body from injury and from losing too much water.
  • What can happen if the skin is too oily? Skin that is too oily can cause acne.
  • What are nails mostly made of? Nails are made mostly of keratin.
  • What do nails do? Nails help to protect the fingers and toes and help to enhance the feeling of touch.
  • What is hair made up mostly of? Hair is made mostly of keratin, just like nails.
  • What are some functions of hair? Hair helps to protect the body from losing heat, and hair around the body helps to keep dust and other particles from getting into the eyes, lungs and other parts of the body.