Integumentary+(example)



The integumentary system is involved in body protection. For humans the integumentary system includes the skin, hair, nails and glands associated with each. The first line of defense against foreign invaders such as viruses, bacteria, and parasites is the integumentary system.

Skin
The skin is a complex organ made of many different kinds of cells. The outer most layer of skin is made of dead cells that contain large amounts of a common protein called **keratin**. This outer layer of skin is constantly being sloughed off and regenerated. The outer layer is called the **epidermis**.

The diagram to the left shows the epidermis as a very thin layer of cells on the surface of the body.

Below the epidermis is a layer that does not rapidly regenerate throughout the life of an animal. **This layer is called the dermis**. The dermis contains a large amount of collagen and elastin fibers which give the skin its elastic properties. The dermis contains blood vessels of the circulatory system which provide the cells with nurishment and carry away waste products.

The dermis also contains nerve endings that communicate to the brain. These nerves comprise part of the nervous system. These nerves communicate sensations such as temperature and texture from the skin to the brain.

Hair
Hair, like the epidermis, is made from the protein keratin. Hair originates from follicles. Follicles are the part of the hair below the skin and are embedded into the dermis layer of skin. The regrowth of hair from the dermis is possible by the presents of stem cells at the base of each follicle.

Hair serves many functions in the mammalian class of animals. Hair is important for insulation, protection, and decoration. Hair, such as those that make the whiskers of many mammals, interact with the nervous system's sense of touch.

Humans have relatively little hair as compared to many of their mammalian family members.

Nails
As with the skin and the hair, the nails of the fingers and toes are composed of cells that have become keratinized (hardened by the protein keratin).

Finger nails have the function of protecting the ends of the fingers and toes. The bones of the skeletal system that end at the tips of the fingers and toes benefit from the added armor the nail provides. Nails also provide us with aid in handling small objects as well as with many of the delicate jobs our hands must accomplish in order for us to survive.

Hair - wikipedia University of Pittsburgh
 * References**


 * //By: Mr. Griffith//**