Global bioheat model for quick evaluation of the human physiological thermal profiles under differing conditions.

The paper presents a physical and mathematical model of the thermoregulatory system of the human body. The model takes into account tissue physiology, structure and general physiological parameters such as blood flow. The global response of the body to underlying physiological variations as well as to any change in ambient conditions can be simulated. The analysis is based on a one-dimensional tissue layer and a two-node core and shell array of the entire body. Application of the model indicates that the body is particularly sensitive to ambient changes in the cold, where a slight drop in gain produces an adverse change in the temperature profile of the physiological system. The gain, G, of the feedback system also suggests that it is an essential parameter in determining the range of the negative feedback as well as the sensitivity of the unacclimizated body to its surroundings. It is also the critical parameter to determine how hard the feedback system works to maintain a homeostatic state. At temperature extremes, G either will cause the system to attain beyond the critical temperatures needed for survival or it will cease to cause the system to respond further to any more changes in the external environment.