Body temperature as a health parameter
Body temperature is one of the main health parameters a doctor checks. The human body keeps its core temperature nearly constant at about 37 degrees Celsius (a normal range of roughly 36.5 to 37.5), no matter whether the weather is hot or cold. This stability is part of homeostasis, and it lets the enzymes in our cells work at their best.
How the body controls temperature
When the body is too hot, it sweats and the skin blood vessels widen (vasodilation) so more heat escapes. When it is too cold, it shivers and the skin blood vessels narrow (vasoconstriction) to save heat. The control centre for this is the hypothalamus in the brain, which acts like a thermostat.
Key idea
A body temperature clearly above the normal range is a fever, often caused by infection. A temperature that falls too low is called hypothermia. Both show that heat balance has been disturbed.
Measuring temperature
A thermometer measures body temperature. Modern digital and infrared thermometers are common; the infrared type reads the temperature of the forehead or ear quickly and without contact, which is useful for screening large numbers of people. Temperature can be taken at the mouth, armpit, ear or forehead.
| State | Approximate temperature |
|---|---|
| Normal | About 37 degrees Celsius |
| Fever | Above 38 degrees Celsius |
| Hypothermia | Below 35 degrees Celsius |
Example
At a Malaysian school entrance, a teacher points an infrared thermometer at each pupil's forehead. A reading of 37.0 degrees Celsius is normal, but a reading of 38.5 degrees Celsius suggests a fever and the pupil is sent to the sick bay.
Remember
Body temperature changes slightly through the day and after exercise, so one reading should be judged together with how the person feels and looks.