THE INTEGUMENTARY SYSTEM
Consisting of the skin, nails, hair, sweat glands, and other accessory organs, the integumentary system helps the body maintain a constant state of balanced internal conditions (homeostasis).

Below the body's two layers of skin (the upper layer, or epidermis, and the deep layer, or dermis), blood vessels, receptors, and glands serve vital functions. Beyond providing the dermis with a supply of blood, the blood vessels enable the skin to grow and heal itself.

Receptors such as nerve endings work with other tissues to detect changes in the environment. The body's ability to sense pressure, heat, cold, and pain is based on a diverse network of receptors.

Two kinds of glands in the dermis—sweat glands that emit moisture onto the skin's surface, and oil glands that secrete lubricating liquid at the base of hair follicles—enable the body to maintain homeostasis by removing metabolic waste products and helping ensure the body's internal temperature remains at a steady level.