Autonomic NS

Question 1

What is the difference between a ganglion and a nucleus?

Answer 1

A ganglion is a cluster of cell bodies usually found outside CNS

Nucleus is usually located within the CNS

Question 2

What is the difference between post and pre ganglionic neurons?

Answer 2

Post ganglionic neurons are neurons after synapse in the ganglion

Preganglionic are neurons before the synapse in the ganglion

Question 3

What are the types of ganglia present in somatic nervous system?

Answer 3

Dorsal root ganglia

Question 4

Where are autonomic nervous system ganglia?

Answer 4

Prevertebral (on anterior surface of abdominal aorta) or paravertebral ganglia (run in sympathetic trunk and chain)

Question 5

Where do preganglionic fibers start in somatic nervous system?

Answer 5

In somatic NS: anterior horn of spinal cord

In autonomic NS: cell body is in lateral horn of spinal cord

Question 6

How many neurons from CNS to effector tissue in somatic NS?

Answer 6

Single neuron from CNS to skeletal muscle

Question 7

How many neurons from CNS to effector tissue in parasympathetic NS?

Answer 7

2-neuron chain from CNS to effector organs

Question 8

Where are preganglionic neuron origins in Sympathetic and parasympathetic NS?

Answer 8

Sympathetic in lateral horn of spinal cord (T1 - L1/2) and parasympathetic in CN III, VII, IX, X In abdominal and thoracic viscera. In pelvic viscera theyc come from S2 - S4 (pudendal nerve)

Question 9

How do muscles respond to sympathetic activation?

Answer 9

Always stimulatory

Question 10

How do viscera/smooth muscles respond to autonomic NS?

Answer 10

Depends on what receptor is being acted on they can be either stimulatory or inhibitory

Question 11

What do motor neurons of the ANS do?

Answer 11

Innervate smooth/cardiac muscle and glands

They maintain homeostasis completely subconsciously

Question 12

Examples of glands in head run by ANS:

Answer 12

Sublingual

Submandibular

Parotid

Lacrimal and nasal glands

Question 13

What is the structural difference between axons of preganglionic and postganglionic sympathetic ANS nerves?

Answer 13

Preganglionic are lightly myelinated and short whereas postganglionic nerves are unmyelinated, branch out, and are much longer as they go from ganglion to target tissue.

Question 14

Which autonomic fibers act directly on target tissue?

Answer 14

Sympathetic neurons activating adrenaline and noradrenaline release

Question 15

What is the structural difference between axons of preganglionic and postganglionic parasympathetic ANS nerves?

Answer 15

preganglionic nerves are lightly myelinated and long.

Postganglionic nerves are short and unmyelinated and don’t branch because they are in the target organ.

Question 16

Why does the skin get sympathetic innervation?

Answer 16

Rich in blood vessels

Goosebumps (erector pili smooth muscle)

Question 17

How are sympathetic fibers arranged?

Answer 17

Topographically (T1-T3 head, T4 - T6 Heart, lungs, oesophagus, T7 - T9 Stomach, liver, gallbladder, pancreas, T10 - 11 appendix + colon, T12 - L2/3 Rectum bladder uterus)

Question 18

Where does the superior mesenteric ganglion postganglionic fibers go?

Answer 18

To the same sites as the superior mesenteric artery.

Same is true for coeliac ganglion+artery and inferior mesenteric ganglion+artery

Question 19

What kind of ganglia are the coeliac, sup.mesenteric, and inf.mesenteric preganglionic ganglia?

Answer 19

At preverterbral ganglia

Question 20

What kind of ganglia are located in the sympathetic trunK?

Answer 20

Paravertebral ganglia

Question 21

What ganglia go back to the head for sympathetic innervation?

Answer 21

Superior cervical, middle cervical, and inferior cervical ganglia

Question 22

What 2 ganglia combine in the stellate ganglion?

Answer 22

Inferior and middle cervical ganglia

Question 23

What tissue do preganglionic afferent sympathetic nerve fibers travel in to reach the sympathetic trunk?

Answer 23

White rami communicantes

Question 24

What tissue do post ganglionic efferent sympathetic nerve fibers travel in to reach grey rami communicantes

Answer 24

Preganglionic (myelinated) fibers travel through white communicantes to enter sympathetic trunk and synapse with postganglionic (unmyenilated) fibers which leave through grey communicantes to exit trunk and enter spinal nerves.

NOTE: Not all preganglionic fibers synapse at the same level some move upwards (eg to synapse with postganglionic nerves going to the head) and others move on to meet postganglionic neuron near target tissue.

Question 25

How many paravertebral ganglia are there in the sympathetic trunk?

Answer 25

3 cervical (remember fusions such as the stellate ganglion)

11 thoracic

4 lumbar

4 sacral

1 coccygeal

Question 26

What are the 3 possible pathways for sympathetic innervation?

Answer 26

1) Preganglionic fiber enters sympathetic trunk through afferent white rami communicantes and synapse with poastganglionic nerves in the sympathetic trunk ad post ganglionic fiber exits through grey ramus communicantes.
2) Preganglionic fiber travels to a different level and synapses with post ganglionic fiber somewhere else. (must be able to do so for innervation at things above T1 and below L1/2)
3) Synapse in a distant collateral ganglion anterior to the vertebral column (eg celiac, sup.mesenteric and inf.mesenteric ganglia)