Autonomic Nervous System

Question 1

preganglionic neuron releases what NT?

Answer 1

acetylcholine

Question 2

postganglionic neuron releases what NT?

Answer 2

acetylcholine or norepinephrine (to excite)

Question 3

What are differences between Sympathetic and Parasympathetic ANS with regard to: distribution, preganglionic origin, postganglionic NT, function?

Answer 3

sympathetic (thoracolumbar) is fight or flight, pregang is in thoracolumbar SC, postgang is usually adrenergic, so it releases norepinephrine.

Parasympathetic ANS (craniosacral) is routine visceral/head actions, pregang in sacral SC and brainstem?, postgang is always cholinergic.

Question 4

Why are muscle vessels dilated under cholinergic control (while cutaneous are constricted) during a sympathetic response?

Answer 4

shifting blood flow to more important areas, but not sure why it’s cholinergic.

Question 5

Parasympathetic does not innervate:

Answer 5

cutaneous vessels, muscle vessels, and sweat glands

Question 6

3 parasympathetic nerve pathways

Answer 6

Cranial Nerves (later)
C10 nerve (Vagus Nerve)
Sacral Spinal Cord

Question 7

Vagus Nerve Parasympathetic Pathway

Answer 7

Parasympathetic. pregangs travel down axon and synapse on “terminal ganglia” in abdomen and thorax. postgangs then go to submucosal or myenteric plexuses to innervate smooth m., cardiac m. or gland.

Question 8

Sacral spinal cord Parasympathetic Pathway

Answer 8

Parasympathetic. S1-S3 innervates pelvic viscera. Pregang goes from sacral cord through ventral root, spinal nerve, ventral branch, sacral plexus, pelvic nerve. then synapses on pelvic plexus and then postgangs branch to pelvic viscera.

Question 9

route of all sympathetic nerves

Answer 9

SC –> dorsal/ventral root –> spinal nerve –> ramus communicans –> sympathetic trunk

Question 10

Head Sympathetic Pathway

Answer 10

Ventral Root –> Spinal Nerve –> Ramus Communicans –> SYmpathetic Trunk

–> ansa subclavia –> cervical sympathetic trunk

synapses on cranial cervical ganglion

postgang goes down carotid arteries and branches.

Question 11

Neck Sympathetic Pathway

Answer 11

Ventral Root –> Spinal Nerve –> Ramus Communicans –> Sympathetic Trunk

Synapses on the cervicothoracic ganglion

postgang:
vertebral nerve –> rami communicantes –> cervical spinal nerve –> dorsal/ventral branches to muscles and skin

Question 12

Body Wall/Limbs/Tail Sympathetic Pathway

Answer 12

Ventral Root –> Spinal Nerve –> Ramus Communicans –> Sympathetic Trunk

Synapses on sympathetic trunk ganglia (paravertebral ganglia)

Postgangs:
rami communicantes –> spinal nerve –> dorsal/ventral branches to muscle/skin

Question 13

Thoracic Viscera Sympathetic Pathway

Answer 13

Ventral Root –> Spinal Nerve –> Ramus Communicans –> Sympathetic Trunk

Synapse at cervicothoracic and middle cervical ganglia

postgang: cardiosympathetic nerves branch from ansa subclavia and with vagus nerve.

Question 14

Abdominal Viscera Sympathetic Pathway

Answer 14

…sympathetic Trunk –> splanchnic n

synapse at prevertebral ganglia - celiac, cranial mesenteric, caudal mesenteric, renal, and gonadal ganglia.

post gang go tonerve plexuses on abdominal arteries

Question 15

Pelvic Viscera Sympathetic Pathway

Answer 15

…sympathetic trunk –> lumbar splanchnic n –> caudal mesenteric plexus

synapses at caudal mesenteric ganglion

postgang:
hypogastric n –> pelvic plexus –> branches to pelvic viscera