6.3 Neuro Anatomy & Physiology - The Autonomic Nervous System

Question 1

What are four organs that the sympathetic nervous system controls that the parasympathetic does not?

Answer 1

• Arrector pili
• Sweat glands
• Skin blood vessels
• Skeletal blood vessels

Question 2

Which of the somatic/autonomic nervous system is voluntary vs involuntary?

Answer 2

Somatic: Voluntary
Involuntary: Autonomic

Question 3

What are the names of the two neurons in the 2-neuron chains of the autonomic nervous system?

Answer 3

• Pre-ganglionic
• Post-Ganglionic

Question 4

Where do pre-ganglionic cell bodies originate?

Answer 4

Brain or spinal cord

Question 5

Where do post-ganglionic neurons originate?

Answer 5

Outside the CNS

Question 6

How many neurons in a typical somatic nervous system efferent pathway?

Answer 6

One

Question 7

Which neurotransmitter does the pre-ganglionic neuron always use to communicate with the post-ganglionic neuron?

Answer 7

Acetylcholine

Question 8

What neurotransmitter is most commonly used in the post-ganglionic neurons of the sympathetic nervous system? What are the exceptions?

Answer 8

Noradrenaline is most common.

Ach is used for sweat glands

Adrenaline is used when innvervating the adrenal medulla

Question 9

What neurotransmitter does the parasympathetic nervous system exclusively use?

Answer 9

Ach

Question 10

What structures does the sympathetic nervous system innervate?

Answer 10

• Visceral organs
• Adrenal gland
• Vascular smooth muscle
• Sweat glands
• Arrector pili

Question 11

What structures does the parasympathetic nervous system innervate?

Answer 11

Visceral organs (head, neck, trunk, genitalia)

Question 12

What responses to alpha-1 and alpha-2 receptors have?

Answer 12

Smooth muscle contraction

Question 13

What response to beta-1 receptors have?

Answer 13

Cardiac muscle contraction

Question 14

What response to beta-2 and beta-3 receptors have?

Answer 14

Smooth muscle relaxation

Question 15

Are the pre/post–ganglionic fibres of the sympathetic nervous system long or short?

Answer 15

Short pre, and long post

Question 16

In which sections of the spine can neuronal cell bodies from sympathetic pre-ganglionic neurons be found?

Answer 16

Thoracic and lumbar

Question 17

Where do fibres of the lateral horn leave the spinal cord?

Answer 17

Ventral root

Question 18

Which type of sympathetic ganglia are paired and which are single

Answer 18

Paravertebral: Paired
Prevertebral: Single

Question 19

What do paravertebral ganglions supply?

Answer 19

• Vascular smooth muscle
• Arrector pili
• Visceral organs of the head, neck, and thorax
• Many other things

Question 20

What do prevertebral ganglions supply?

Answer 20

Visceral organs of abdomen and pelvis

Question 21

Draw a diagram of the paravertebral membranes attaching to the spinal cord and spinal nerves

Question 22

How does the sympathetic chain increase the versatility of pre-ganglionic neurons?

Answer 22

These neurons can relay messages up or down the sympathetic chain, which spans the entire spinal cord, allowing for the message to be delivered to a greater number of places

Question 23

What are the two fates of a sympathetic pre-ganglionic neuron that innervates paravertebral ganglia?

Answer 23

After innervating paravertebral ganglia:
1. Innervates spinal nerve (skeletal muscle)
2. Innervates splanchnic nerve (visceral targets)

Question 24

What do prevertebral ganglia innervate? With what nerves?

Answer 24

Internal organs of pelvis and abdomen. This occurs via splanchnic nerves

Question 25

What hormones are released by the adrenal medulla when it is directly innervated by a pre-ganglionic sympathetic fibre? Why is this significant?

Answer 25

• Noradrenaline (20%), adrenaline (80%)
• This is significant because noradrenaline is the primary messenger neurotransmitter of the sympathetic nervous system

Question 26

With which cells do preganglionic sympathetic fibres synapse in the adrenal medulla? Why is this unusual?

Answer 26

• Synapse with chromaffin cells
• Unusual because there is no post-ganglionic fibre!

Question 27

Where can muscarinic receptors be found?

Answer 27

• Cardiac muscle
• Smooth muscle
• Glands

Question 28

Where does the parasympathetic nervous system arise from in the CNS?

Answer 28

Brain stem and sacral region (S2-S4)

Question 29

How long are the pre-/post-ganglionic fibres in the parasympathetic nervous system?

Answer 29

Long pre, short post

Question 30

Why do we need less parasympathetic innervation than sympathetic?

Answer 30

Because the parasympathetic nervous system supplies less structures

Question 31

Which organ regions do the parasympathetic nerves from the brainstem supply?

Answer 31

Head, abdomen, thorax

Question 32

Where do parasympathetic nerves exit the sacral spinal cord (cross-sectionally speaking)?

Answer 32

Ventral horn/ventral root

Question 33

Why is there rarely a lateral horn in the sacral region of the spine?

Answer 33

Not enough autonomic innervation to form a discrete horn

Question 34

Which nerves do the sacral spinal nerves form when leaving the spinal cord?

Answer 34

Pelvic splanchnic nerves

Question 35

Which axons comprise the autonomic plexus?

Answer 35

• Sympathetic postganglionic axons
• Parasympathetic preganglionic axons
  + Some visceral sensory axons

Question 36

List four major autonomic plexuses

Answer 36

• Cardiac plexus
• Pulmonary plexus
• Abdominal aortic plexus
• Sup and Inf Hypogastric plexus

Question 37

What neurotransmitters are always released by preganglionic and postganglionic sympathetic fibres?

Answer 37

Pre: Ach
Post: NE