It’s always strange to me how the body prefers 72 to 75 degrees F on the outside but 98 F on the inside. Anything approaching equalizing of interior with exterior temperature results in heat-related illness.
We basically run on tiny combustion engines. Exothermic reactions.
We aren't a passive 98 degrees, we would be hotter if it wasn't cool enough outside. Higher heat would cause different cellular structures to become misshapen, leading to system breakdown. I'd be like trying to run a cpu cooling loop with boiling water.
And I'd add to that that if our thermal dissipation is overwhelmed, our internal heat build up. To do that heat dissipation, we need to have an environment that suck out more heat out of us than what we produce. If the environment is too hot, the heat build up and as Deadrek says, our internal inner workings beak down.
That why we sweat. Water suck out a lot more heat than air, because it wants to saturate the ambiante air, and to do that it suck up our body heat to become steam. Rince and repeat (literally).
But once the air is to humid, it gets more and more difficult for our sweat to evaporate, which makes it ineffective. That why we can kinda survive in a 90°C + sauna (albeit not for long, but for a different reason), but not in a 37°C (98°F) 100% humidity place like some tropical rainforest. At least, not without specialized acclimatation and survival techniques.
There's actually theoretically an endothermic reaction we do. E coli can undergo an endothermic reaction if it has enough zinc. It's entirely possible this is why we have an appendix. I'll link studies if anyone is interested
As shown in Fig. 2A, Zn2+ titrations began with an exothermic heat reaction, which was followed by a late endothermic reaction. This characteristic exothermic-to-endothermic transition suggests the presence of at least two sets of independent Zn2+ binding sites, accounting for the exothermic and endothermic heat reactions, respectively.
Escherichia coli was the most commonly identified microorganism in the appendiceal lumen (83.4%; 34.7% as a single entity)
E. coli was found in 76.2% of the cultures of the appendiceal lumen in patients with uncomplicated appendicitis (35.7% as the only pathogen) followed by P. aeruginosa (21.5%) and K. pneumoniae (14.3%) (Table 3).
E. coli was also the predominant microorganism in complicated appendicitis (96.4%; 63.1% of them in combination with other bacteria).
Our findings indicated that dietary Zn supplementation significantly increased the feed-to-weight ratio of broilers during the experimental period under heat stress.
Basically, not only should we all be supplementing with zinc during hotter months, but also this has indications for the purpose of the appendix and possibly a way to make air conditioning out of our feces.