L36 Autonomic Nervous System

Question 1

Summarise the sympathetic and parasympathetic nervous systems

Answer 1

Sympathetic - FIGHT OR FLIGHT

Parasympathetic - REST AND DIGEST

Question 2

What are the major differences between the somatic and two divisions of the autonomic motor efferent systems (sympathetic and parasympathetic)?

Answer 2

Location of CNS motor neurones 
Mono- V.S. Di-synaptic pathways to effector 
Autonomic Ganglion cells 
Axon lengths & myelination 
conduction velocity and significance 
Neurotransmitters and receptors

Question 3

What type of motor neurones are in the lateral horn?

Answer 3

Autonomic motor neurones

Question 4

What type of motor neurones are in the ventral horn?

Answer 4

Somatic motor neurones

Question 5

What is a mono-synaptic neurone?

Answer 5

Directly innervate effector using one synapse (one long axon)

Question 6

What type of pathway is a somatic motor one?

Answer 6

A monosynaptic one

Question 7

What type of pathways do sympathetic and parasympathetic neurones follow?

Answer 7

Di-synaptic one.

Question 8

What does it mean for the sympathetic and parasympathetic system to be di-synaptic?

Answer 8

An axon from a cell body in the CNS makes a connection with neurones in the PNS which are collectively known as autonomic ganglion cells. The autonomic ganglion cell has postganglionic fibres/axons that travel to the effector.

Question 9

Why is the voluntary motor system faster at processing than the autonomic nervous system?

Answer 9

1) There’s always a delay at synapses. (The somatic pathways is mono-synaptic).
2) The diameter of axons in the somatic motor pathway tend to be wider and have more myelin.

Question 10

Which fibres of the autonomic system have myelin?

Answer 10

Only the preganglionic fibres of the autonomic system have any myelin.

Question 11

What is a difference between axon lengths in the sympathetic and parasympathetic system?

Answer 11

The preganglionic fibres in the sympathetic system are shorter than in the parasympathetic system.

The postganglionic fibres in the sympathetic system are longer than in the parasympathtic system.

Question 12

Do both the sympathetic and parasympathetic system only make use of acetylcholine?

Answer 12

No ( the parasympathetic system may only use acetylcholine however the sympathetic system also uses norepinephrine)

Question 13

How does the parasympathetic system use acetylcholine as a neurotransmitter ?

Answer 13

Motor neurones of the parasympathetic system use acetylcholine to stimulate parasympathetic ganglion cells. These parasympathetic ganglion cells then release acetylcholine to inner are target cells.

Question 14

How does the sympathetic system use both acetylcholine and norepinephrine?

Answer 14

Sympathetic ganglion cells are stimulated by acetylcholine neurotransmitters which were released by the motor neurones of the sympathetic system.

These ganglion cells then release norepinephrine to inner age target tissues.

Question 15

Why can the parasympathetic division also be called the cranio-sacral division?

Answer 15

It is called cranial-sacral division because there are lots of motor neurones in the brain stem inside the cranium that give rise to parasympathetic outflow as well as lots of motor neurones in the bottom of the sacral cord that give rise to parasympathetic outflow.

Question 16

How many pairs of cranial nerves are there?

Answer 16

12

Question 17

How many cranial nerves have parasympathetic outflow and which ones are they?

Answer 17

4 cranial nerves have parasympathetic outflow. These nerves are:

3rd Occulomotor nerve

7th Facial nerve

9th Glossopharyngeal nerve

10th vagus nerve

Question 18

What does the 3rd Cranial nerve which is called the Oculomotor nerve, innervate?

Answer 18

From the EDINGER-WESTPHAL nucleons Innervates neurones in the Ciliary Ganglion supplying the sphincter pupillary muscle of the iris (construction in response to light) & ciliary muscle (accommodation of the lens at ‘near’).

AKA basically eye muscle movement

Question 19

What does the 7t Cranial nerve which is called the Facial nerve, innervate?

Answer 19

Innervates neurones in the pterygopalatine ganglion supplying the lacrimal gland (tear production) and the geniculate ganglion to 2 of the salivary glands.

Question 20

What does the 9th cranial nerve which is called the Glossopharyngeal nerve, innervate?

Answer 20

Innervates neurones in the optic ganglion supplying the largest (parotid) salivary gland.

Question 21

What does the 10th Cranial nerve which is called the Vagus nerve, innervate?

Answer 21

Innervates numerous ganglia supplying the heat, liver, and the respiratory, digestive, urinary and reproductive systems.

Question 22

Are there any sympathetic motor neurones in the brain?

Answer 22

No

Question 23

Why can the sympathetic division also be called the thoraco-lumbar division?

Answer 23

All motor neurones that give rise to sympathetic outflow are all in the spinal cord( none in the brain). They exist from T1-T2.