From Big Medical Encyclopedia

THERMOLYSIS — process of allocation by a live organism to the environment of the warmth which is released as a result of the power transformations providing life activity of an organism, and (or) received from the outside.

T. it is carried out by direct carrying out heat through fabrics according to their heat conductivity, convection (transfer of heat moving blood, the air moving at a body surface), radiation (infrared «the radiation of a body), evaporation of water from a body surface and mucous membranes of respiratory tracts. At ambient temperature 20 ° the thermolysis carrying out and convection makes about 31%, radiation — 44%, evaporation — 21%; other heat can be absorbed by the food and water coming to an organism (due to distinctions in temperature).

Size T. it is regulated by physiological mechanisms, to-rye provide constancy of body temperature (see. Body temperature ) at temperature variations of the environment and speed of heat production of an organism (see. Heat production ). The most important mechanism of regulation of T. vasomotor reaction is. Thanks to decrease in a tone of vessels the blood stream can increase from 1 to 100 ml/min. on 100 cm3 of fabric in skin of the person. T. at the same time increases due to increase in heat conductivity of skin and the strengthened transfer of heat blood from deeply located fabrics to a body surface, and T. various sites of an integument it is various. Vasoconstriction of skin respectively reduces T. Other important mechanism of regulation of T. at the person sweating is. At hard work of sweat glands about 1,5 l of sweat an hour are allocated (sometimes more). Efficiency of this mechanism of regulation of T. it is very high if to consider that for evaporation of 1 g of water 0,58 kcal are spent. Sweating is made on all body surface, however its intensity on different sites of skin can differ considerably.

At a row patol. states, in particular at to fever (see), regulation of T. it is broken that is connected with influence of the pyrogenic substances (see) on the centers of thermal control or with a direct injury of peripheral mechanisms T.

See also Thermal control .

Bibliography: Dolnik V. R. Bio-energetics of modern animals and origin of a gomoyotermnost, Zhurn. general biol., t. 42, No. 1, page 60, 1981; To and N d r about r I. S., Dyomin D. M. and Ratner E. M. Physiological principles of sanitary and climatic division into districts of the territory of the USSR, M., 1974; Koshcheev B.C. Physiology and hygiene of individual protection of the person from cold, M., 1981; Ecological zoophysiology, under the editorship of. A. D. Slonima, JI., 1982; In e n z i n-g e r T. Heat regulation, homeostasis of central temperature in man, Physiol. Rev., v. 49, p. 671, 1969; Cabanac M. Temperature regulation, Ann. Rev. Physiol., v. 37, p. 415, 1975.

K. P. Ivanov.