The functioning of the body organs and the activity of the muscles produce great quantities of the heat through the constant chemical reactions and oxidation which goes on in the living organism.
The normal mouth temperature 98.6 F, is higher than the skin temperature , which is 97.5 F, the rectal temperature, 99.6 F, is higher than the mouth temperature, and the temperature of the internal organs is even higher.
The temperature in the liver can be as high as 101 F. or much higher under normal conditions.Like all good and efficient machines, the body machinery is provided with a cooling system or heat dissipation mechanism to balance the heat production, or the body would destroy itself from the internal combustion going on inside of it.
The heat loss or dissipation from the body is accomplished by convection, evaporation, radiation and expulsion.
Perspiration of the entire body surface, which goes on at all times, even in cool weather ( invisible perspiration), cools the body by its evaporation and by actual expulsion of hot water from the body.
The skin loses heat also by radiation.Of the course, much depends on the surrounding temperature and humidity of the air, and on the temperature of the objects in close proximity with the body.
The loss of the body heat through the skin is about 88% of the total heat loss, the rest is lost by evaporation from the lung by exhaling moisture amounting to about 7 % and another 3% by the heat lost by expiring heated air from the lungs, the balance of 2 % is lost through the loss of the heat by the body excretions urine and feces.
Under normal outside conditions, the body heat production and loss is well balanced. But when outside conditions, such as high humidity and great heat, prevent loss of the body heat, the loss of body heat is not great enough to counterbalance the heat produced in the body and that gained from the outside, and it will therefore result in heat stroke