Why does it get cold when the temperature is high?

Posted on Mar 9, 2022      271

The presence of a fever is an extremely unpleasant condition. A sick person experiences weakness, lack of appetite, muscle pain and, of course, a constant feeling of cold, which makes you want to wrap yourself in several layers of blankets and not get out of bed.

Meanwhile, fever is a genuine gift of evolution, thanks to which animals can fight various infections, creating unbearable conditions for the reproduction of various microorganisms. And we have to pay for this gift - in particular, with ill health.

So what causes these nasty colds? It’s all because of pyrogens - substances that cause our body to raise the temperature. Pyrogens are various viruses, bacteria, or products of tissue decay within the body itself. Pyrogens can be exogenous (entering the body from the external environment) and endogenous (formed in the body). Imagine that a sick person sneezed next to you in a crowded bus: bacteria entering the body come into conflict with white blood cells and because of decomposition products are formed, which are pyrogens. Toxins that accumulate when bacteria multiply are also pyrogens.

The hypothalamus is our body’s main thermostat

The resulting substances are powerful irritants to the hypothalamus, the center responsible for the body’s thermoregulation. The hypothalamus “decides” to raise the body temperature to fight the bacteria and uses the means available to it. In particular, it reduces sweating, narrows the blood vessels at the extremities and reduces blood flow to the skin. The temperature of the skin decreases, limiting heat loss, which increases the temperature inside the body. Because of the decrease in surface temperature, a person feels chills, and there is a persistent desire to cover himself with a blanket.

But after the temperature reaches a certain value, the hypothalamus dilates the skin vessels: the feeling of cold is gone, and the person feels hot.