The overheating of the body

The overheating of the body - the accumulation in the body of excess heat in the result of failure of the main (if high ambient temperature) mechanism of heat - isolation and sweat evaporation; the overheating of the organism is characterized by the elevation of body temperature and impaired water-salt balance. In a healthy person heat dissipation is balanced with heat production (see Thermoregulation). The heat loss from the body surface by convection and radiation stops at an ambient temperature of about 33 degrees. At higher ambient temperatures, the heat transfer takes place only through evaporation of sweat. Delay sweat evaporation (100% humidity, water-resistant clothing, and so on) can lead to overheating of the body at temperature 33 - 34 degrees. High heat production (muscle, liver disease, diarrhea, circulatory failure, lack of water in the body contribute to the development of overheating of the organism. Especially easily overheat infants and the first years of life. At the beginning of overheating of the organism occurs weakness, palpitations, then the noise in the ears, headache, dizziness.
Progressive overheating of the body leads to violation of hemodynamics, to hypoxia and changes in the Central nervous system. Forecast in some cases severe may experience heat stroke, sometimes with fatal outcome. Treatment - see Heat stroke.
Messy drinking water without electrolytes can lead to water intoxication and seizures. It is therefore using salted soda - see Drinking regime. In hot shops necessary cooling and airflow. Clothes should not impede the evaporation of sweat.
Resistance to overheating of the organism individually different, changes in training, adaptation and acclimatization.

The overheating of the body (hyperthermia) - fever when exceeding the physiological features of the regulation of the intensity of the effects that impede heat transfer and contributing to the accumulation in the body of excess heat. For temperature homeostasis at maximum heat production (work) and enters into the body of 100-150 kcal per hour due to the heat radiation of the required total heat dissipation in the environment around 500-600 calories/hour. The heat loss from the body surface by convection and radiation stop when the temperature equalization of the skin and the environment (an average of 33 degrees); at higher ambient temperatures heat is only due to the latent heat of evaporation of water from the surface of the body. With intensive evaporation of sweat maximum allocation (about 1 liter per hour) provides a value for h 580 kcal of heat and maintenance of homeostasis during operation at temperatures is about 50-60 degrees. Termination of office or sweat evaporation (100% humidity, water-resistant clothing, stay in the water, and so on) can lead to overheating of the body already at 33-34 degrees. Overheating contribute to the scarcity of water in the body and insufficient replenishment of its losses since then. With the loss of heat through evaporation contained in the body of water 10-12% of body weight, the body temperature rises (despite the continuing separation of sweat) in connection with a thickening of the blood, shortness of circulation and heat transport to the periphery of the body.
Resistance to overheating of the body is reduced in acute infections and convalescent, liver disease, diarrhea, circulatory failure, anaesthesia, blood loss and shock. Especially easily overheat infants and the first years of life. In a hot climate slight temporary P. O. occurs frequently in the sun and in some industrial environments, not subjectively Omusati, despite a number of objective changes (tachycardia, changing reflex excitability and others). Progressive P. O. accompanied by a "heat exhaustion, alternating with periods of excitation; the increase of gas and heat production; first increase and then a gradual decrease in blood pressure and blood flow. Hemodynamic lead to hypoxia, which plays a major role in the dysfunction of the Central nervous system in P. O. Performance declines, with acute physical stress occurs shortness of breath; possible syncope and collapse. Increases permeability to protein of blood vessels and the blood-brain barrier. The secretion of digestive glands inhibited. Phagocytic activity of leukocytes and reticuloendothelial system increases as resistance to muscle relaxants. Secretion of corticosteroid hormones moderately increases, decreases the content of ascorbic acid in the adrenal glands and iodine in the thyroid gland. Sugar, lactic acid and residual nitrogen in the blood increase. The increase in total nitrogen metabolism in overheating of the body is variable and is not connected with the height of hyperthermia. Overheating up to 41 degrees threatens the development of heat stroke (see). After a light acute P. O. thermoregulation (see) is unstable for several hours; after higher P. O. malfunctions may occur for several days. Individual resistance to P. O. varies widely and varies significantly in training, adaptation P acclimatization (see).