FIGURE 9-1 Anatomy of human skin showing skin layers, hair follicles, sebaceous and sweat glands. The degree of the burn is determined by the depth of damage. First degree burns involve only the epidermis, and cause edema and erythema without vesiculation. Second degree burns involve the epidermis and dermis, and usually result in blisters or dermal necrosis. Third degree burns extend into the subcutaneous fat, muscle, or bone and often cause substantial scarring. SOURCE: Reprinted from Sams and Lynch, 1990, with permission from Churchill Livingstone.

biochemical and physiological activity of the adnexal structures (eccrine sweat glands, sebaceous glands, and apocrine glands), the skin assists in the regulation of body temperature and the excretion, manufacture, and absorption of electrolytes, vitamins, nitrogenous matter, and other organic substances.

The epidermis occupies the outermost layer of skin and is paramount to maintenance of mammalian homeostasis. It, among the three layers of skin, offers the human body considerable protection from entry of noxious chemicals and microorganisms; it prevents uncontrolled outward movement of fluids, electrolytes, and many organic substances. Large burns due to thermal, chemical, or ultraviolet injury, if they destroy large amounts of epidermis, can lead to an enormous loss of fluid, electrolytes, proteins, and other organic materials through an