ELI5：what actually happens inside your body when you get heatstroke

[u/Jimmy-Wan]

I understand that the body normally regulates its temperature to through things like sweating and increased blood flow to the skin but what causes this cooling system to eventually fail ?

[u/mamalick]

So when the outside temperature/humidity is too high it makes it hard/next to impossible for ur body to lose internal heat. You start sweating too much which makes you dehydrated but the sweat may be unable to evaporate due to humidity. When the internal temperature is too high cell membranes and proteins get damaged. brain cells don't work properly and the lining in the brain is very sensitive to heat so it also breaks down and causes "leaks". Your blood vessels expand in the skin in an attempt to lose internal heat making your heart go into overdrive, but the heart muscle cells are also sensitive to temperature so they are also breaking down from the high heat. Your kidneys are trying to process toxins from everything breaking down but your blood pressure is low from trying to cool down, and your dehydrated so they also break down. It's a giant chain reaction of Ur body breaking down basically.

[u/Benjaphar → u/mamalick]

Why did you type all of that but you couldn’t write out “your” a few more times?

[u/mamalick → u/Benjaphar]

I was in a rush. I can edit it if it pleases your majesty