- Peripheral Nervous System—Autonomic Nervous System 93
The Urinary System (Advanced)
■ Th e sympathetic and somatomotor eff erents inhibit
urination.
■ Th e parasympathetic fi bers activate urination.
■ Parasympathetic fi bers excite bladder wall contraction
and inhibit internal urethral sphincter constriction.
■ Sympathetic fi bers inhibit bladder wall contraction,
excite internal urethral sphincter constriction,
and tonically inhibit the parasympathetic
ganglion.
■ Somatomotor eff erents provide tonic activation of
the external urethral sphincter.
■ Male reproductive mnemonic: Parasympathetic —
Point and Sympathetic — Shoot.The Cardiac Refl ex (Advanced)
■ Th e glossopharyngeal nerve carries aff erents from
the carotid body and carotid sinus.
■ Th e vagus nerve carries aff erents from the aortic
bodies and aortic arch baroreceptors.
■ Th e glossopharyngeal and vagus nerves project
to the solitary tract nucleus, which, via the nucleus
ambiguus, induces heart rate deceleration.
■ Th e rostral ventrolateral medulla provides tonic
sympathetic stimulation to the intermediolateral cell
column of the spinal cord to produce heart rate
a c c e l e r a t i o n.