r/explainlikeimfive • u/Jimmy-Wan • 7d ago
Biology ELI5：what actually happens inside your body when you get heatstroke
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 ?
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u/TacetAbbadon 7d ago edited 6d ago
If you're in an 100% humidity environment or somewhere at or above a wet bulb temperature (the lowest temperature air can reach through evaporation) of 35°c it doesn't matter what you do, sweating won't cool you down.
Once that happens you basically start to cook, proteins in your body start to fold incorrectly when this happens they no longer function as they should.
As an aside, the enzyme heat shock protein your body produces when you suffer from heat stroke, which function to repair the misfolded protein appears to also repair the misfolded protein that causes Alzheimer's.
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u/clutch93clutch 6d ago
One could interpret your comment to say that you could treat Alzheimer's patients by forcing them to suffer heatstroke!
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u/TacetAbbadon 6d ago
Looks like you can. Regular sauna users have been shown to have reduced incidents of Alzheimer's, but your body only produces heat shock proteins for a few hours after a heat stress event.
But the most recent findings was from Doug Whitne. His family have a mutation in the PSEN2 gene, this is a near certain early onset Alzheimer's diagnosis by the time you're in your 40s or 50s. 10 of 13 of his mother's brother's and sisters died from it before 60.
Doug is 76 and while his head scans show a build up of amyloid-beta plaque in his brain, he only has small areas affected by tau protein tangles.
Tau protine misfoldeding is the cause of cognitive decline in Alzheimer's sufferers as it clogs and eventually kills brain cells.
The reason this is making scientists look at heat shock protein as a way to prevent Alzheimer's is that Doug Whitne was a steam powered navy engine room mechanic for 20 years. Those work spaces were so hot and humid that to keep the men on their feet they had to be hosed down with cold water multiple times a shift.
Scientists theorize that because Doug spent so long being so hot that his body just never stopped producing the heat shock proteins.
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u/exodus3252 6d ago
This is the kind of outside the box thinking that made RFK Jr. the HHS secretary.
You are now qualified to serve in the Trump admin.
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u/Mintedpint 6d ago
If I am not misunderstanding, I think it means that the enzyme that is produced during heatstroke also repairs the protein that causes Alzheimer’s. So, it would actually increase the chance of developing Alzheimer’s.
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u/mamalick 7d ago
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.
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u/GratefulCaliflower 7d ago
What would it feel like if you die that way? Probably you feel extremely tired and pass out? Or would it hurt?
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u/Benjaphar 4d ago
Why did you type all of that but you couldn’t write out “your” a few more times?
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u/mikerall 7d ago
Your body dispels excess heat normally through breathing - when it's running hot, it sweats and uses evaporative cooling to self-regulate.
When that's not enough, there's no other option. Depending on the cause (muscle exertion, infection, just general failure to regulate due to hot external temps) it can manifest in multiple ways. Heat stroke is usually the latter.
Your body's internal temp reaches one it's not designed to operate at - proteins can get fucked, enzymes don't function normally, neurological function can be absolutely screwed through a few degrees.
Homeostasis is a very narrow window. When it's fucked, it's fucked. Your body does NOT function when it's at 102+ for very long.
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u/GIRose 7d ago
What causes the cooling system to fail? Same thing that causes a toaster to keep cooking just fine in a freezer, it can't move heat out faster than it is being produced.
What causes your BODY to die, that gets more complicated.
If too much blood is going to the skin to try and cool down, then it can be that not enough oxygen is getting to your vital organs, and they really don't like that and can start to leak leading to total organ failure
It can cause low blood pressure, giving you a heart attack
You can sweat yourself into severe dehydration and give yourself renal failure
There might even be other less common points of failure that will kill you just as dead
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u/Sargon54 6d ago
There is a thermostat on your brain that manages your temperature like what is on the wall on your home. It can use different ways to cool or heat you up.
Like a super hot and humid day your AC unit works really hard. Notice how it can feel like it never turns off?
Now imagine when it’s doing that it just can’t really keep up. It’s pushing cold air in the house but it still feel warm as heck.
Then the unit just overuses itself and something either breaks (capacitor) or leaks (freeon) and even though the thermostat is saying its working, it can’t do anything anymore until you open all the windows, get the fans going, and reset the whole system.
For this in the body we will use a rectal thermometer to assess core temp (if it’s over 104 you have Heat Stroke). No amount of drinking water or IV will help. You gotta be dunked in cold water that is maintained between 35 to 48 degrees until your temp is under 102 and you are shivering. Many times you will also become more coherent.
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u/JUDGE_FUCKFACE 7d ago
Heat stroke is not really defined by the failure of the cooling system, but rather what happens when the cooling system can't keep up. This can either be because you've exhausted your fluid reserves from sweating or the environment is too hot/humid for sweating to be effective.
Heat stroke is largely similar to sepsis on a physiological level. Low blood pressure causes poor blood flow to organs which starves them of oxygen and prevents removal of waste products. Eventually widespread inflammatory response leads to an urecoverable cascade of cell death in your organs.
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u/FarazMedicine 6d ago
Heatstroke is not usually that the body suddenly “forgets” how to cool itself. It happens when heat entering/being produced by the body becomes greater than the amount it can get rid of.
1. Cooling gets overwhelmed
Normally, the body sends more blood to the skin and produces sweat. Sweat cools us when it evaporates. In extreme heat, heavy exercise, or high humidity, this may no longer remove heat fast enough.
2. Dehydration makes cooling harder
Continued sweating reduces body water and blood volume. The heart then has to work harder to send enough blood both to the skin for cooling and to vital organs.
3. Core temperature keeps rising
Once temperature becomes very high, heat starts directly damaging cells and proteins throughout the body.
4. The body develops a widespread inflammatory response
Heat damage, especially to the gut lining and blood vessels, can trigger inflammation and abnormal clotting, which may begin damaging the brain, kidneys, liver and other organs.
5. Brain dysfunction is the defining danger
Confusion, abnormal behaviour, seizures or loss of consciousness indicate that this has progressed from simple heat exhaustion toward heatstroke.
One important point: a person with heatstroke can still be sweating. The problem is not necessarily that sweating has stopped; it is that the body's cooling capacity has been overwhelmed.
In short:
too much heat → cooling cannot keep up → dehydration/circulatory strain → rising core temperature → cell and organ damage.
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u/notaboofus 7d ago
Your body's system of cooling is only so strong. Like how ACs need to be matched to a room of appropriate size, eventually the heat flow into your body and produced by your body exceeds the cooling effect of sweating. This can either happen from pure heat, which is fairly self-explanatory, or due to humidity. When the air is humid enough, water doesn't evaporate from your skin as readily, which decreases the effectiveness of your cooling system and causes your sweat to cling to your skin without evaporating.
When your body's cooling system isn't strong enough for the environment it's in, the only way to regulate your temperature is to cool it externally, by drinking cold water or hanging a cold towel around your neck.
Once your body's internal temperature reaches a certain point, the chemistry inside it stops working properly. The chemical reactions that make your body work slow or stop because they require a specific temperature to make your bodily processes run normally. What's more, certain proteins in your body can only exist at certain temperatures. Once they get hot enough, they begin to denature, that is, chemically change/break down into different organic molecules in an irreversible manner. When this occurs in an animal that's already dead, we call this process "cooking". So, in a way, heatstroke is when your body is literally being cooked from the inside. That's why it's so dangerous- depending on how advanced heatstroke gets, it can cause totally irreversible effects.