|skin (skĭn) Pronunciation Key
The outer covering of a vertebrate animal, consisting of two layers of cells, a thick inner layer (the dermis) and a thin outer layer (the epidermis). Structures such as hair, scales, or feathers are contained in the skin, as are fat cells, sweat glands, and sensory receptors. Skin provides a protective barrier against disease-causing microorganisms and against the sun's ultraviolet rays. In warm-blooded animals, it aids in temperature regulation, as by insulating against the cold.