Our urine is stored in the bladder. The bladder maintains a constant contact with a part of our brain known as the pontine micturition centre (I spent 20 seconds typing that), which is a collection of cell bodies located in the brainstem. It detects the rise and fall of pressure in our bladder, and it tells us to pee. So this is the area which sends out impulses urging us to urinate whenever our bladders reach the limit. However, the signal can be overridden by the prefrontal cortex, the region of our brain that plans complex cognitive behavior, which sends a restraining signal to the brainstem, otherwise a major part of human civilization would have been dedicated to inventing hand-carry toilets.
|Image: en. wikipedia.org|
Gazelles wet themselves with a lion in hot pursuit. Pigeons often become incontinent when chased by wild-eyed toddlers. Laboratory rats have a nasty habit of peeing all over researchers’ hands.--Slate.com
Perhaps peeing could help turn off the predator's appetite?
info: http://www.slate.com/articles/news_and_politics/explainer_extra/2011/10/peeing_your_pants_why_do_people_urinate_when_they_re_scared_.html?tid=sm_tw_button_chunky http://en.wikipedia.org/wiki/Prefrontal_cortex