11.6 : 体温升高

A fever or pyrexia occurs when the body temperature rises above 100.4 degrees Fahrenheit.

Fever is a natural defense mechanism that activates the immune system to fight infections.

The hypothalamus regulates and maintains core body temperature.

It signals the body to cool down or produce heat in response to hot or cold temperatures.

Fever occurs when the temperature set-point is disturbed by pyrogens, a substance that starts the fever response.

Immune cells detect the pyrogens produced by pathogens such as bacteria and viruses.

These immune cells bind to the bacterial cell walls, releasing inflammatory cytokines such as interleukin-1, interleukin-6, and tumor necrosis factor.

These cytokines stimulate the hypothalamus to produce prostaglandin-E2, which triggers a "cold" reaction in the hypothalamus and establishes a higher set-point.

As a result, the hypothalamus stimulates the body to produce heat, which causes a fever.

Another condition that elevates body temperature is hyperthermia, where the thermoregulatory mechanism exhausts and fails to balance the extra heat generated by the body.