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  #1  
Old 09-14-2009, 11:21 PM
Mr Buttons Mr Buttons is offline
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Why the sudden urge to pee when going from warm to cold?

I've worked in kitchens and grocery stores, both place w/ walk-in coolers. I've also noticed many times, after walking out/into the walk in coolers, a lot of times you'll have to pee a whole lot more than 20 seconds ago when you walked into the cooler. This effect seems to be about twice as bad for females as men, which is no surprise since they always pee more anyways.

Just wondering if anyone has any ideas why this happens. My hypothesis is maybe the body's trying to save heat in the core, and somehow that's making the bladder contract. Anyone else's answers/guesses are more than welcome.

FTR, I'm talking drastic, sudden temperature changes. Like going from 75 degrees into 35 degrees or below.
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  #2  
Old 09-15-2009, 12:15 PM
Hennessy Hennessy is offline
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Good question, also why do some (all?) people get cold when they have to pee? As if having to pee causes it.
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Old 09-15-2009, 01:00 PM
dolphinboy dolphinboy is offline
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And while you're at it, why does sudden immersion in warm water always make me want to pee?
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Old 09-15-2009, 02:40 PM
tanstaafl tanstaafl is offline
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When you are in a cold environment your body constricts the blood vessels near your skin to reduce heat loss. This has the side effect of increasing the amount of blood in the vessels in your bodies core. Your kidneys interpret this increase in blood volume as an increase in the amount of water in the blood and so do what they are supposed to do and start removing some of it.
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Old 09-15-2009, 04:01 PM
Tom Tildrum Tom Tildrum is online now
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Quote:
Originally Posted by dolphinboy View Post
And while you're at it, why does sudden immersion in warm water always make me want to pee?
Note to self: stay out of dolphinboy's jacuzzi.
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Old 09-15-2009, 06:59 PM
dracoi dracoi is offline
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Quote:
Originally Posted by Mr Buttons View Post
FTR, I'm talking drastic, sudden temperature changes. Like going from 75 degrees into 35 degrees or below.
For what it's worth, this kicks in for my wife under much smaller temperature changes. 15 degrees F can be enough.

I heard an evolutionary biology fan say that it was an adaptation to encourage primitive humans to pee near their caves so the smell would deter to predatory animals. I suspect that opinion is not worth the air it was spoken with, though.
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Old 09-15-2009, 08:47 PM
armedmonkey armedmonkey is online now
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Quote:
Originally Posted by tanstaafl View Post
When you are in a cold environment your body constricts the blood vessels near your skin to reduce heat loss. This has the side effect of increasing the amount of blood in the vessels in your bodies core. Your kidneys interpret this increase in blood volume as an increase in the amount of water in the blood and so do what they are supposed to do and start removing some of it.
That's a good bit wrong.

Your kidneys don't interpret anything. The O.P. has a good question, but it's about the urinary bladder, not the kidneys. The kidneys are filters, not much more. The cold causes the muscles around the bladder to contract, and you feel like you have to urinate.

Let me break it down. The urinary bladder is surrounded by skeletal (voluntary) muscle, just like the ones in your arms and legs. When you get cold, your arms and legs get stiff. They get stiff because the muscles contract due to decreased blood flow. What happens if the urinary bladder muscles contract? Hell, man, that's how you pee.

tanstaafl is half right with the idea that it's a mechanism to retain heat in the core of the body, but it's muscle - not kidneys.
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Old 09-16-2009, 01:59 AM
Mr Buttons Mr Buttons is offline
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Originally Posted by Hennessy View Post
Good question, also why do some (all?) people get cold when they have to pee? As if having to pee causes it.
If you're speaking of "piss shivers", that a whole other topic. Which The Master covered before. Every guy/girl I've talked to has experienced a piss shiver at one time or another. I'm settling for Cecil's answer of it's the nerve ending at the end of your spine.

I'm just wondering why drastic temperature changes affect the bladder. Granted 2000 years ago, I doubt our ancestors ever experienced a temperature drop of 40 degrees in 10 seconds or so. I'm guessing it's an evolutionary quirk which didn't mean a damn thing until we learned refrigeration, but I'd still like to know why it happens.
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Old 09-16-2009, 05:27 PM
dracoi dracoi is offline
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Quote:
Originally Posted by Mr Buttons View Post
I'm just wondering why drastic temperature changes affect the bladder. Granted 2000 years ago, I doubt our ancestors ever experienced a temperature drop of 40 degrees in 10 seconds or so. I'm guessing it's an evolutionary quirk which didn't mean a damn thing until we learned refrigeration, but I'd still like to know why it happens.
Even if we ascribe its origin to evolution, there doesn't have to be a "why" behind it. If it didn't affect your ability to breed successfully, then it wasn't influenced by natural selection one way or the other.

I also think our ancestors probably did experience temperature differences that were pretty dramatic. Building a fire in a cave requires no real technology and does a good job of keeping you warm. A little basic tech and you can build a sweat lodge that could be 100+ degrees warmer than the outside.
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