OK, you’re going about your business, when you get that “urge” telling you that its time for a bowel movement. You have no urinary “urge”. In fact, urinating is the furthest thing from your mind. Immediately after moving your bowels, you start urinating. Why?
Does fecal urgency somehow suppress urinary urgency? Or does the act of defecation somehow promote urination?
You pulled your abdominal muscles in to speed the dump along; that squeezed your bladder and presto! Urination!
The urge to pee was there the whole time, but the need to dump was so overwhelming that you didn’t notice anything else.
The ahem mass in your bowels was pressing against the urethra and holding the urine in all by itself, so your muscles got lazy and didn’t bother to assist. When your bowels emptied, nothing was standing in its way, so the urine obeyed the call of gravity.
As your bowels moved, something inside pressed against your bladder and triggered a reflex, so the bladder emptied even though it wasn’t full.
I’ve experences it - My wag is that the bladder expands because there is more room to expand after #2 leaves. The expanded bladder signals the nerves that’s it time for #1.
Another idea… in my experiences, I can pee at just about ANY time. I only get a real bad urge to take a whiz a couple times a day, but if I think about pissing for a few minutes, I can feel my bladder start mumbling. After taking a crap, I’m sitting there, going “Ahh… that was good shit,” and something in the back of my mind probably says, “Hey, as long as you’re here, why not take a leak and double the fun?” Hence… the piss/poop duality.
I’d say that’s not it. In my experience, I get the #1 urge the very second I start executing, errr, the #2 manoeuver. In other words: at that stage, the expansion room for the blatter is almost negligable. My WAG would still be that it is some sort of nerve reflex that’s being triggered.
Cisco, I realise your tuna sandwich may not taste as good anymore after reading this, but this is hard science, goll durnit. We’ll get to the bottom of it!
If I’m taking a #1 and then find I need a #2, I feel very disappointed because it means I can’t have that wonderful relief feeling of #2 followed by #1.
I think it’s just a “one out, all out” kind of manoeuver that goes on simply because it might as well.
It’s due to the fact that both functions are governed by the parasympathetic nervous system. In fact, emptying of the bladder and rectum are two of the very few parasympathetic functions that are even partially voluntary.