Autonomic Nervous System

Question 1

What is the autonomic nervous system also called?

Answer 1

Visceral nervous system

Question 2

What system makes up the basic anatomy of the ANS?

Answer 2

Two-neuron system

Question 3

Describe the structure of the two-neuron system

Answer 3

– Pre-ganglionic fibers originate from the CNS

– Post-ganglionic fibers originate from autonomic ganglia

Question 4

Where are the fibre origins of the sympathetic nervous system?

Answer 4

Pre-ganglionic
Thoracolumbar

Post-ganglionic
Paravertebral Chain Prevertebral Ganglia

Question 5

Where are the fibre origins of the parasympathetic nervous system?

Answer 5

Pre-ganglionic
Craniosacral

Post-ganglionic
In or Near Target Organ

Question 6

What structures do the parasympathetic system control?

Answer 6

Eye (III)
Lacrimal gland (VII)
Salivary glands (VII)
Heart (X)
Lung (X)

Upper GI tract (Nervi erigentes -> pelvic ganglia)

Bladder (Nervi erigentes -> pelvic ganglia)

Genitalia (Nervi erigentes -> pelvic ganglia)

Question 7

What structures do the sympathetic system control?

Answer 7

Structures in head and neck (Eye, blood vessels, salivary glands, etc)

Heart
Lungs
Adrenal medulla
Liver (prevertebral medulla)
GI tract (prevertebral medulla)
Bladder
Genitalia
Blood vessels (paravertebral sympathetic chain (bilateral) -> segmental outflow)
Sweat glands etc (paravertebral sympathetic chain (bilateral) -> segmental outflow)

Question 8

What provides sympathetic supply to organs in the head?

Answer 8

Internal carotid (sympathetic) plexus

Question 9

Describe the anatomy of the sympathetic trunks

Answer 9

Each sympathetic trunk extends as far as the atlas and they fuse with each other in the ganglion impar opposite the coccyx There are superior, middle and inferior cervical ganglia, the latter often fuses with the T1 ganglion to form the Stellate Ganglion that lies on the neck of the 1st rib

Question 10

What are the three sympathetic prevertebral ganglia?

Answer 10

Celiac ganglion
Superior mesenteric ganglion
Inferior mesenteric ganglion

Question 11

What does the celiac ganglion supply?

Answer 11

Adrenal gland
Liver
spleen
stomach
small intestine
proximal colon
kidney

Question 12

What does the superior mesenteric ganglion supply?

Answer 12

Distal colon

Question 13

What does the inferior mesenteric ganglion supply?

Answer 13

Distal colon
Rectum
Urinary bladder
Genitalia

Question 14

Describe the autonomic motor reflex

Answer 14

Impulse travels from sensory afferent neuron to spinal cord where it joins the interneuron. Signal then passes from sensory afferent neuron to interneuron to preganglionic fibre.

Signal then goes to autonomic ganglion then postganglionic where signal takes effect on the target tissues

Question 15

What myelinated the postganglionic fibre of the autonomic nervous system?

Answer 15

Trick question, post ganglionic fibre in non-myelinated and preganglionic fibre is lightly myelinated

Question 16

What phrase related to the parasympathetic nervous system do you associate with a tiger on a tree in Mrs Simpsons class?

Answer 16

Rest and digest

Question 17

What phrase is often used to describe the action of the sympathetic nervous system?

Answer 17

Fight or flight

Question 18

What effect does What does the superior mesenteric ganglion supply?

Answer 18

Decreased rate of contraction

Question 19

What muscle of the eye has parasympathetic innervation and what does it do?

Answer 19

Pupillary constrictor muscle, causes miosis

Question 20

What muscle of the eye has only sympathetic innervation and what does it do?

Answer 20

Pupillary dilator muscle, causes mydriasis

Question 21

What effect would a sympathetic agonist have on the eye?

Answer 21

Mydriasis (dilation)

Question 22

What effect would a parasympathetic agonist have on the eye?

Answer 22

Mydriasis (dilation)

Question 23

What is the function of the ANS when bladder is filling?

Answer 23

Sympathetic control predominates
• Relaxation of detrusor muscle
• Contraction of internal sphincter muscle

Question 24

What is the function of the ANS when bladder is full?

Answer 24

Parasympathetic control predominates
• Contraction of detrusor muscle
• Relaxation of internal sphincter muscle

Question 25

What is the basic physiology of sympathetic and parasympathetic innervation?

Answer 25

• may oppose or compliment
• may (rarely) have same effect (e.g. saliva)
• Some tissues only innervated by one

Question 26

What is the basic physiology of autonomic reflex arcs?

Answer 26

Autonomic reflex arcs exist for visceral control

• Path of afferent fibers can explain referred pain

Question 27

What is are the generalised effects of the ANS?

Answer 27

• Parasympathetic – “rest and digest”

* Sympathetic – “fight or flight”

Question 28

What are varicosities?

Answer 28

Typically, long postganglionic sympathetic fibers lead from the sympathetic chain to the target organ where they are terminated with bulbous enlargements called varicosities. This modified axon endings release a neurotransmitter (in the case of sympathetic nervous system norepinephrine) into its surroundings

Question 29

Discuss the sympathetic innervation of the adrenal gland

Answer 29

Preganglionic sympathetic fibers synapse on chromaffin cells
Chromaffin cells release adrenaline (~80%) and noradrenaline (~20%) into systemic circulation
-> widespread tissue response

Question 30

What do all pre-ganglionic neurons in the parasympathetic sympathetic system release?

Answer 30

ACh, acetylcholine for nicotinic receptors

Question 31

What do all postganglionic parasympathetic neurons

release?

Answer 31

ACh, acetylcholine for muscarinic receptors

Question 32

What do postganglionic sympathetic neurons release?

Answer 32

• Most release noradrenaline

* Some release ACh (i.e. sweat glands)