Physiology of Human Thermoregulation – Heat Balance

Abstract

In homeothermic animals including humans, the internal body temperature is maintained nearly constant through physiological and behavioral adjustments. Heat balance is achieved by balancing the heat produced within the body and the heat dissipated to the environment. Heat production is generated through the catabolism of nutrients in the body’s cells. Energy is released via this process, most of which is converted to heat in the body. Heat production is affected by a number of factors such as sex, age, body composition, physical activity, ambient temperature, food intake and specific diseases. To achieve heat balance, the mechanisms of heat dissipation to the environment have to be activated, which are classified in two categories: dry and wet heat exchange. Dry heat transfer is the sum of heat exchange via conduction, convection and radiation while wet heat exchange is mainly the evaporation of water from the body surface. The above information is analyzed in foreign language publications and journals, while the relevant knowledge in Greek remains minimal. The purpose of this review is to summarize the existing knowledge about the human thermoregulatory system and the principles of heat balance. The factors affecting heat production and the heat exchange mechanisms with the environment are also analyzed. To achieve this, a comprehensive search was made in the Pubmed database using terms related to the human thermoregulatory system as well as the mechanisms of heat production and heat loss. The physiological importance of these mechanisms is demonstrated by the importance of heat balance for preventing accidents and diseases associated with heat stress.