What stops us from peeing ourselves at night?
In: Biology
Alright, so two sets of muscles keep your pee in. The internal and external sphincters. The internal sphincter is NOT under your control. The subconscious (Autonomic nervous system) controls it. The external sphincter however is under your direct conscious control. That is why you can control the urge to pee, i.e., actively denying your subconscious plea to pee.
Now, inside your subconscious pee control system are two factions fighting for control: the parasympathetic system, which wants to keep the internal sphincter closed and the sympathetic system which wants to open the same. In the normal human body, its generally the parasympathetic with the upper hand, so the bladder normally stays closed. That is what stops you from peeing yourself at night.
When the bladder fills up, the stretch receptors in the bladder tell your brain that the bladders full, and sends a notification to the conscious part “Hey man, you need to pee, or in a little while it’s gonna hurt.” When you heed that call, you allow the external sphincter to open and also allow the sympathetic part of the internal sphincter to take over, at which point you allow the pee to pass out, aided by the positive pressure in your abdomen and the detrusor muscle.
This entire system is almost copy pasted in case of your pooping system which also why you don’t poop yourself at night. Newborns and infants do poop and pee themselves because human beings as a species shows collective premature birth when compared to other mammals, due to our massive brains. This system matures as they grow older.
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