Heat is generally produced by the action of the thyroid hormones, and muscles play an important role in it. The constant body temperature is, however, maintained by nervous regulation at the hypothalamus.
In healthy individuals, the body temperature is somewhere between 36.5°c and 37.5°c. It increases marginally during the day. The lowest temperature is between 2:00 a.m. and 4:00 a.m.
The term “fever” is used when the body temperature increases above 37°c. Shivering, chills and vasoconstriction in the skin are seen. The body temperature is increased by decreasing the loss of heat. At the same time, the production of heat in the organism increases. Muscle tone increases and spasms may occur.
Fever could be the outcome of a number of stimuli such as bacteria and their endotoxins, viruses, yeasts, spirochetes, protozoa, immune reactions, several hormones, and even some medications.