Anatomy
Parasympathetic Nervous System
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Parasympathetic Nervous System
, Parasympathetic System, Parasympathetic Nerve
See Also
Autonomic Nervous System
Sympathetic Nervous System
Autonomic Dysfunction
Cholinergic Toxicity
Anticholinergic Toxicity
Definitions
Parasympathetic Nervous System
Part of
Autonomic Nervous System
with activity that typically counters the
Sympathetic Nervous System
Energy conserving (anabolic) system activated in rest and relaxation situations
Contrast with the
Sympathetic Nervous System
, an energy expending system activated in times of stress
Physiology
Activity
Decreases pupil size (
Miosis
) and contracts ciliary
Muscle
(accommodation)
Stimulates
Saliva
ry WATERY secretion (contrast with viscous secretion by the
Sympathetic System
)
Decreases
Heart Rate
and
Blood Pressure
Stimulates bronchoconstriction and
Bronchi
al gland secretion
Increases gastrointestinal activity (peristalsis) and secretion
Relaxes gastrointestinal sphincters (e.g. anal sphincter in
Defecation
)
Stimulates
Urethra
l relaxation and
Bladder
contraction
Mediates
Erection
(contrast with ejaculation mediated by the
Sympathetic System
)
Anatomy
Craniosacral division of the
Autonomic Nervous System
Signals originate
Sacral spinal cord (S2 to S4) supplies urinary and
Gastrointestinal System
s
Brain Stem
nucleii (
CN 3
,
CN 7
,
CN 9
,
CN 10
)
Vagus Nerve
(
CN 10
) has broad, far ranging activity (lungs, heart, gastrointestinal)
Limited roles by
CN 3
(pupil/ciliary constriction),
CN 7
(tears/
Saliva
) and
CN 9
(
Saliva
)
Preganglion
Neuron
s
Synapse
at cranial autonomic ganglia or in terminal ganglia near target organs
Transmitted to target organ
Images
Pathophysiology
See
Cholinergic Toxicity
(e.g.
Organophosphate Poisoning
)
See
Anticholinergic Toxicity
(e.g.
Anticholinergic Medication
)
References
Goldberg (2014) Clinical
Neuroanatomy
, Medmaster, p. 54-60
Netter (1997) Atlas Human Anatomy, ICON Learning, p. 152-4
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