Thermoregulation

Abstract

Thermoregulation is a process that allows us to maintain body core internal temperature. Without thermoregulation, it would be impossible to maintain body functional capacity. All thermoregulation mechanisms are designed to return body homeostasis. This phenomenon is a state of balance which can fluctuate within a very narrow range. Body core temperature regulation is very precise occurring within a very narrow range. When the body is exposed to very high surrounding temperatures, and increased metabolism, heat dissipation becomes important for existence. In humans, the primary mechanism of heat dissipation, particularly when ambient temperature is higher than skin temperature, is evaporative heat loss secondary to sweat secretion from eccrine glands. The provision of a stable core body temperature is vital in countless bodily processes regulated enzymatically. Factors affecting normal body core temperature include environment, exercise intensity, and disease, while there are four ways of heat loss: convection, conduction, radiation, and evaporation. If skin temperature is greater than that of the surroundings, the body can lose heat by radiation and conduction. Disruptions in any of these mechanisms can result in unstable body core temperature. The body’s ability to regulate its temperature is compromised by extreme environmental conditions. For example, in hot and humid conditions, it is difficult for the body to dissipate heat away from itself via heat exchange because of the moisture in the air and small temperature gradient between the skin and ambient air, resulting in an elevated temperature. In frigid climates, a great deal of metabolic work is necessary to produce core body heat and prevent it from leaving the body through blood flow to the body surface, resulting in a slight drop in body temperature. Exercise can interrupt normal body core temperature due to the increased metabolic rate and thus heat production. Bloodstream conveys the heat to the skin to dissipate the heat to the surroundings through sweating and radiation. In case that heat dissipation mechanisms during exercise are dysfunctional, a significant increase in body core temperature occurs. This may cause heat fatigue or heatstroke. Unhealthy individuals frequently have difficulties in controlling body core temperature, due to altered capacity to activate regulatory mechanisms to initiate heat exchange. In individuals, with hypertension, as an example, blood circulation to the skin surface is limited, resulting in reduced heat transfer away from the body. Thermoregulatory function, that is, heat dissipative responses such as skin blood flow and sweating to an increased body temperature, is critical during physical work or exercise in warm and hot conditions and during hyperthermia. Thermoregulatory function is associated with fitness level, age, and physiological status and diseases. Aerobic exercise training and acclimation to the heat improve heat dissipative responses in healthy subjects.