When you pee, your body empties the bladder, but sometimes you can push and more pee will come out. So how come your body doesn’t get rid of all the pee at once?

Question

When you pee, your body empties the bladder, but sometimes you can push and more pee will come out. So how come your body doesn’t get rid of all the pee at once?

In: 240

Answer 1

So the answer is sorta complex.

1. Generally speaking, it’s kinda painful. Your bladder is an organ and if it changes shape quickly it can hurt. If you’ve ever been cathed at the hospital and had your entire bladder emptied at once you already know this. Nurses trick for patient comfort is to let it out slowly, pause to let the bladder adjust, and then let more out.
2. Your bladder is sort of opposite in terms of how we view musculature. You can’t flex your ‘pelvic’ muscles to pee because muscle flexing means you are retaining urine, while relaxing them causes urination. When you have sympathetic activation “fight or flight” you have urine retention (muscles tense). But when you are back into a parasympathetic state i.e. the “breed, feed, peed” state, you relax those muscles and can urinate. It’s also generally speaking, why men don’t urinate when they ejaculate. Ejaculation is a sympathetic activating activity. Your muscles are flexed, and thus no pee escapes. It also may be why female ejaculation takes a fair amount of manipulation/relaxation (although that part is just my speculation).
3. It’s hard to ‘relax your way’ into peeing more. When the bladder senses it’s no longer stretched, it just goes back to normal. The way around this, should you want to get it all out is to increase intrabdominal pressure leaning forward/rocking. Sidebar: sometimes when people do this (called double voiding) it can also cause an ache.