[Slightly vulgar shower thought]
How does excretion (defection or urination) affect the thermal energy of the body? The substance retains some thermal energy from the body, but does losing that substance cool the body in any way?
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Technically excretion does lower the total thermal energy of the body as it is leaving your body with the excretion, but it does not really in itself cool down the temperature of the body as the temperature is the same as your body (unless you define cooling down as negative change in the thermal energy needed to remove to lower object’s temperature to zero K). Though if for example you drink cold water it does cool your body very slightly and urination could be thought of as dumping of used coolant.
I’m not sure about number 2, but your bladder actually acts as a heat sink since piss is mostly water. Water has a crazy high heat capacity, so it drains heat from your body. It’s a common tip for camping in extreme cold temperatures to not go to bed with a full bladder since your body has to spend some amount of calories warming up the piss.
I don’t see how it makes a difference in the cold. It’s already body temperature, so there would be a thermal equilibrium. Heat loss is a function of the body’s surface area, which is unaffected.
But the piss will eventually leave your body, so all of the heat energy that went into it is going to be dumped out.
Well it starts at body temperature, and if it stays in thermal equilibrium, then it doesn’t require energy to maintain. It wouldn’t make a difference, you’d be losing the same amount of heat energy either way.
Based on what others have said, I think the answer is that it isn’t really in equilibrium. If the bladder is in contact with tissues that are warmer on one side than the other, then it will basically act as a thermal conductor to move heat away from your core.
Your body isn’t a closed system. You are constantly radiating heat away, and you are constantly burning calories to maintain your body’s core temperature. So the bladder is a tank full of mostly water inside that is draining those valuable calories and then will just be pissed away.
It’s not like the bladder is radiating heat away when it’s inside the body. Heat doesn’t just get used up, it has to go somewhere. If it was in equilibrium it would just increase your thermal mass and have no effect.
Like I said though, I think the issue is that it’s constantly moving heat away from the core to the lower abdomen where it can be radiated or conducted away.
When you say “cool the body” do you mean decrease the average temperature, decreasing the total thermal energy, or decreasing the total potential thermal energy? For the last two options the answer is a pretty clear yes because, even though our bodies try to efficiently consume food, poop still does have a bunch of calories in it and none of our waste leaves the body at 0K.
What about relative energy (energy per mass) - if poop is less energy dense than the protein/fat of your tissues, excreting it should increase your energy density
Oh true, that’s another way to read the question.
I don’t have an exact answer for you, but I can share this: Part of military training up here in the Arctic involves a lot of cold weather training. And an officer explicitly told us that if we felt the slightest urge to shit or piss, take care of it ASAP - “Heating up all that crap is energy better spent heating up the rest of you”
Is your poo requesting political asylum?
The heat capacity of the human body is around 3.0kJ/kg°C, and the one of urine is likely close to water (4.2kJ/kg°C). As such when urinating a person loses proportionally way heat than mass.
So if you’re feeling hot perhaps relieving yourself might give you a bit more comfort. Although you’ll likely do it anyway, as you drink more water.
For faeces it’s trickier, as their heat capacity varies quite a bit depending on the moisture content, from 4.6 to 0.4kJ/kg°C. I’d guess that for healthy individuals it should be the same effect but in smaller degree as urine.
(And thus the No Poop Challenge becomes acclaimed as the solution for energy waste.)
