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Water balance
Water enters the organism from three sources meeting in the extracellular space: drinks 1200 ml, foodstuffs 1000 ml, constituting an exogenic water, and 300 ml of endogenic water as a result of metabolic oxidation of fats, proteins and carbohydrates. An excretion of water is carried out through: kidneys 1400 ml, persperation 1000 ml (through the lungs 500 ml and 500 ml via skin), with feces — 100 ml. In the norm a daily intake of water is 2500 ml (35-40 ml/kg of body mass or 1.5 1/m2 of body surface). A daily entry of liquid and its excretion by the organism is expressed by balance. In the norm a water balance is equal to 0. When the entry prevails over the losses of water (a positive balance) if organs of excretion do not response immediately, edemas appear. In negative water balance a feeling of thirst arises that is a subjective manifestation of dehydration, and if it is not satisfied the organism comes into collapse and dehydration shock. Losses associated with persperation are in close connection with the mechanism of thermoregulation and proportional to human body surface and mass. A volume of persperation is based on the following calculation — 14.4 ml/kg of mass or 0.5 1/m2 of body surface. Besides, persperation increases by 500 ml per every 1°C of temperature elevation over 37°C, and in tachypnea — by 500 ml per every 10 inhalations over 16 usual ones per minute. In the period of prolonged cavitary operations a loss of water is intensified by persperation from open cavities of the body (up to 100 ml/h). It is necessary to take this into account as pathologic losses. To pathologic losses of liquid one refers also the liquid being lost with vomiting, diarrhea, drainages, and so on. Дата добавления: 2015-02-05 | Просмотры: 601 | Нарушение авторских прав |