الفهرس 
Anatomy of SkinOnly 14 pages are availabe for public view
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Abstract
T
he skin covers the entire external surface of the human body and is the principal site of interaction with the surrounding world. It serves as a protective barrier that prevents internal tissues from exposure to trauma, ultraviolet radiation, temperature extremes, toxins and bacteria. Other important functions include sensory perception, immunologic surveillance, thermoregulation and control of insensible fluid loss.
Burn injury is defined as an area of tissue damage caused by the effects of heat. It may result directly from the transfer of thermal energy or indirectly when some other form of energy is converted into thermal energy. Examples of the latter are the skin burn seen in electrocution (electrical energy), burns occurring as a result of friction (physical energy), and thermal energy resulting from a chemical reaction (chemical burns). Traditionally injuries resulting from wet heat sources, such as hot water and steam, are known as scald.
Burns and scalds tend to be seen at the extremes of age and have highest incidence in those less than two years old. Twenty percent of burns occur in children aged up to four years and of these 70% are scalds. Sixty percent of burns occur in patients aged 15 to 64 mostly as a result of contact with flames. About 10% occur in people aged over 65.
Thermal injury results in a spectrum of local and systemic homeostatic derangements that contribute to burn shock. These include disruption of normal cell membrane function, hormonal alterations, changes in tissue acid-base balance, hemodynamic changes, and hematologic derangement.
Plastic surgeons are consulted for burns that present to the emergency department. The first decision to be made is whether the injury may be cared for at the presenting facility or should be transferred to a designated burn center. This assessment will include the size of the burn, the depth of the burn, the risk of morbidity, associated injuries (e.g., inhalation injury or trauma) and patient co morbidities .
One of the major problems that face any burn surgeon is the decision on the nature of treatment (conservative treatment versus operative treatment). In the case of an operative procedure, a decision is needed on when and how to excise the burn wounds and to determine accurately the depth of the lesion and thereby the extent of tissue involvement.
The key decision in the treatment of thermal injuries is the exact determination of the depth of the burn wound. Traditionally, the evaluation of burn depth has involved serial clinical examinations which involves primarily subjective judgments. Various objective examination techniques, supplementing the clinical diagnosis have been evaluated.
Burn depth, along with the extent of the burn (TBSA) and age of the patient, are primary determinants of mortality following thermal injury. The depth of injury is also a major determinant of a patient’s long term function and appearance.