Why does a frightening situation often cause uncontrollable urination?

Question

Due to the fact that the urinary bladder is innervated by the autonomic nervous system, and that sympathetics are responsible for increasing muscle tone of the sphincter, while decreasing the muscle tone of the bladder wall (while the opposite is true for parasympathetic stimulation) it seems counter-intuitive for a "flight-or-fight" situation to cause this. Am I missing something? Ok, obviously I am, but what?

Answer 1

I'm not certain about this, but there are some examples like "merciful syncope", in which the sight of one's own blood or dramatic injury causes excessive parasympathetic output to the heart, which drops cardiac output and results in fainting -- which is paradoxical, because one would expect predominantly sympathetic output in such a situation. It's possible that a similar paradoxical-reaction might occur with micturition (urination), such that excessive parasympathetic discharge occurs in response to sudden fright, and removes sympathetic inhibition, resulting in urination.