Jim McDonald's How Mother Nature Will Try to Kill You: Hyperthermia

That's "too much heat":

Making Light: Heat Stress: Jim Macdonald: Welcome back to Environmental Emergencies Theatre. In our last thrilling episode we saw Hypothermia. It's summertime now, so it's time to talk about Heat Stress, aka Hyperthermia. Hyperthermia, like her twin sister Hypo, can kill you deader'n dirt by this time tomorrow.

We do best when our core temperature is within one degree either way of 98.6 degrees Fahrenheit (37 degrees Celsius). Below that, you're into hypothermia. Above it, you have hyperthermia.

We generate heat all the time.... The name for keeping the interior environment of our body within certain narrow limits (pH, salinity, and so on) is homeostasis. The human body has several systems that are tasked with maintaining our internal temperature. It's a mammal thing. We regulate our internal temperature by internal means so we don't have to crawl into cracks or sun ourselves on rocks.

Regardless of the exact origin of the heat in the body, it has to go somewhere, because the body is very heat-sensitive. Even when it's forty below and we're wearing our parkas, we still need to bleed off excess heat. All we're doing is controlling the rate. If the core body temperature hits around 105 degrees Farenheit, the proteins in the brain start to denature, and within ten to fifteen minutes... you're in deep, deep trouble...

Pleasant planet you're guiding us around, Mr. MacDonald.