Magazine article Nutrition Health Review

The Temperature of the Human Body

Magazine article Nutrition Health Review

The Temperature of the Human Body

Article excerpt

Before studying the characteristics of fever, it is important to first have an understanding of how the body regulates its temperature.


Humans are homeothermic, which means that their body temperature should always remain the same with almost unvarying consistency. In other words, it does not change in accordance with the weather or with atmospheric conditions. Whether it is summer or winter, whether people live in the desert or the far north, their body temperature will always stay around 98.6°F. This is the core temperature (inside the body) and not the more superficial reading of 97.7°F. provided by taking the temperature with a thermometer placed beneath the arm. In the animal kingdom the other homeotherms are mammals such as goats and cows and so forth, as well as birds.

The word horneo therm is used to describe the opposite of poikilotherm. Poikilothermie animals' body temperature varies in accordance with the ambient temperature of their environment. The temperature of these animals will rise when the sun is shining and the weather is hot, such as during the summer, for example, and will fall when it is cloudy, during the night, and during the cold seasons of the year.

One well known example can be used to illustrate these variations of body temperature in response to climatic condition: the lizard. When stretched over a stone, basking in the sun, its body temperature can rise higher than 104°F. During colder periods of the year, the lizard's temperature can fall to 68°F., 50°F., or even 41 °R, depending on the temperature of its environment. Given that the speed of its metabolism is dependent on its internal heat, in summer the lizard can flee with lightening speed, but when the weather turns cold it moves so slowly that it can be trapped without any difficulty.

Some animals, such as hibernating mammals, combine both systems: they are homeotherms in the spring and summer, but with the arrival of winter, they fall into the slumber of hibernation and their body temperature matches that of their environment.

It was once common to make a distinction between warm-blooded and cold-blooded animals, but this terminology has been abandoned, since the lizard, for example, theoretically a cold-blooded animal, can have a body temperature much higher than we humans, who are technically warm-blooded beings! …

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