What temperature is dangerous for humans

Fever: temperature regulation in the body

Depending on the temperature, different fever levels are distinguished:

  • 36.5 ° C - 37.4 ° C: normal temperature
  • 37.5 ° C - 38.0 ° C: Subfebrile temperature
  • 38.1 ° C - 38.5 ° C: Slight fever
  • 38.6 ° C - 39.0 ° C: Moderate fever
  • 39.1 ° C - 39.9 ° C: High fever
  • 40.0 ° C - 42.0 ° C: Very high fever

There is a "heat regulation center" in the brain, the so-called hypothalamus, part of the diencephalon. It ensures that a largely constant temperature is always maintained in the brain, heart, kidneys and liver by controlling the production and release of heat as required. This Temperature setpoint is set to around 37 ° C. In the event of an infection or other inflammation, this setpoint is adjusted and is higher than the normal 37 ° C. As a result, the hypothalamus gives the command to adapt the "actual value" to the new "nominal value" and to "heat up" the body more intensely.

Chills: heat produced by trembling muscles

The body then tries to reach the higher temperature target value and produces more heat by increasing the metabolism or muscle work. If that happens within a very short time, e.g. B. in an acute severe infection, it comes to the known chills. At the same time, the heat output is throttled by the blood vessels in the periphery of the body contracting and thus preventing heat from being lost through the skin.

The purpose of this increase in the setpoint is to ward off pathogens. An increased body temperature helps the body fight pathogens: By increasing the temperature, the body weakens or eliminates the invaders, because viruses, bacteria and other parasites are adapted to the normal body temperature of 36 to 37 ° C and are damaged at higher temperatures .

Pyrogens: messenger substances that trigger fever

Various substances can increase the temperature setpoint and thus cause a fever (Pyrogens, Greek "pyr" = fire, fever). Pyrogens can not only get into the body from the outside, such as components of bacteria or viruses as well as certain bacterial substances (exotoxins), but they can also enter the body itself as a reaction to infections or Inflammations develop, including interleukin-1, tumor necrosis factor and interferons, which act as messenger substances to reinforce the inflammatory reaction.Bacteria and viruses can stimulate immune cells to produce such fever-inducing substances.