I’ve never seen this aspect dealt with in any of the articles I’ve read about the urinary system
But how your body senses a full bladder isn’t known. Certain proteins can be activated by cells being stretched or squeezed. One gene, called PIEZO2, holds the instructions to make such proteins. PIEZO2 has been shown to play a role in sensing mechanical stimulation, including touch, vibration, pain, and proprioception (the awareness of one’s body in space).
Pee zo 2
You’d think it’d just be pressure receptors inside the bladder, but we’ve gotten a few interesting case studies from astronauts who report urinary retention in zero-g.
Your bladder is just a muscle-bag that stretches and collapses like a balloon depending on its volume, so pressure from the urine wouldn’t change much in zero-g vs normal g.
Makes me wonder if the receptor that triggers the need to pee is under and completely separate from the bladder, activated by the downward force of a heavy bladder laying on it.
Easy enough to test: if you need to pee, hang your torso off the side of the bed or do a handstand or something so the gravitational force on the bladder is reversed – did the urge to pee go away?
Your bladder is just a muscle-bag that stretches and collapses like a balloon depending on its volume, so pressure from the urine wouldn’t change much in zero-g vs normal g.
Have you used, for example, one of those camp showers? Water is heavy. Gravity builds up pressure fairly quickly, and it’s going through a pretty small pipe.
it’s going through a pretty small pipe
Speak for yourself
Urethras are all narrow, regardless of their enormous meat casing, n’est-ce pas?
Pure guesswork because I’m way too lazy to dig:
There’s the actual pressure of the liquid, then the muscles that hold the pee in have to strain more to resist that pressure.
You know what? I liked your answer. You didn’t claim it was truth, and it started a discussion. I think it sounds like a reasonable enough theory, it’s probably weirder than that, because that’s usually how things be, but I like how you think!
Plus someone else would inevitably come up with the same comment anyway as it’s the intuitive answer even if another comment disproves it.
Guesses are fine as long as they’re marked as such, and will often not be that far from the real answer and can trigger someone else to dig deeper and further add.
Even if you end up completely wrong, now that’s a searchable thread with child comments disproving it.
I bet if this comment just claimed this is what happens, nobody would complain and it would have more upvotes. If I tell you I’m 90% sure I’m right, that doesn’t discredit my analysis, I’m just being honest about what I don’t know, at least the reader can make the determination as to whether it’s good enough for them or not. This is social media not a peer reviewed scientific journal.
I see that kind of crap all over politics too. Candidate A is honest and replies with nuances, candidate B makes bold claims, people vote candidate B because A “looks weak and indecisive”.
Eventually we’ll be able to have civilized conversations without mentioning it.
But until then, thank you guys for this awkward but wholesome display of mutual respect.
Whoever downvoted this comment is a very small person.
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At least they stayed on topic and didn’t try to put anyone down.
So is OP.
And that “nonsense” makes perfect sense. Exactly like your sphincter keeps you from shitting your pants, there are muscles that hold your urine in.
What do you think “holding it” means? It means you’re tightening the muscle to prevent flow. The more you have to strain to do so, the more fatigued that muscle gets.
Well this was stupid. Thanks for the explanation, doctor
