<Tr> <Th> FMA </Th> <Td> 9907 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> The parasympathetic nervous system (usually abbreviated PSNS, not PNS, to avoid confusion with the peripheral nervous system) is one of the two divisions of the autonomic nervous system, the other being the sympathetic nervous system . (The enteric nervous system (ENS) is now usually referred to as separate from the autonomic nervous system since it has its own independent reflex activity .) The autonomic nervous system is responsible for regulating the body's unconscious actions . The parasympathetic system is responsible for stimulation of "rest - and - digest" or "feed and breed" activities that occur when the body is at rest, especially after eating, including sexual arousal, salivation, lacrimation (tears), urination, digestion and defecation . Its action is described as being complementary to that of the sympathetic nervous system, which is responsible for stimulating activities associated with the fight - or - flight response . </P> <P> Nerve fibres of the parasympathetic nervous system arise from the central nervous system . Specific nerves include several cranial nerves, specifically the oculomotor nerve, facial nerve, glossopharyngeal nerve, and vagus nerve . Three spinal nerves in the sacrum (S2 - 4), commonly referred to as the pelvic splanchnic nerves, also act as parasympathetic nerves . </P>

When does the parasympathetic nervous system begin to function