Nervous system????????????

During hot summer days, we sweat, and often complain about being exhausted "just from the heat". This discomfort reflects a process that the human body is using to keep its core temperature at a safe level. The body is like a machine, and as every machine creates heat when it uses energy to run, so too does the human body. The body generates heat when it runs its inner metabolic processes. Real is also supplied by the outside environment as hot and humid weather, by hot objects (like furnaces) or hot places (like being inside a chemical suit or firefighter's turnout gear). There are times and situations when heat is not just a discomfort, but dangerous.

The body's internal core temp must be maintained within a fairly rigid range of temperature. This core temperature, is 99.5 degrees, plus or minus 1.8 degrees. Determined to maintain that core temperature, the body strives to strike a balance between the amount of heat produced internally and the amount of beat lost (or gained) to the outside environment. This is done largely through sweat. As sweat evaporates, it takes heat with it. Work harder and the body will crank up the heat exchange system: you sweat more. The internal core temperature stays within safe ranges as long as this heat/cooling mechanism functions properly. But, if it is very hot or humid, if work is near a furnace or other heat source, or workers wear chemical protective clothing, the mechanism of heat exchange can be altered dramatically. When that happens you can get sick.

through the negative feedback system which causes vasoconstriction and sweating.