Autonomic Nervous System

Question 1

To what degree of myelination are the pre- and post-ganglionic fibres?

Answer 1

Pre-ganglionic = small myelinated 
Post-ganalionic= unmyelinated

Question 2

Name some structures that ANS neurones effect?

Answer 2

Smooth muscle
Cardiac muscle
Glands
GI neurones

Question 3

What are the 2 divisions of the ANS?

Answer 3

Sympathetic (fight or flight)

Parasympathetic (rest and digest)

Question 4

What regions of the spinal cord to sympathetic nerves originate?

Answer 4

Thoracic T1-12

Lumbar L1-2

Question 5

What is convergence?

Answer 5

Many preganglionic fibres synapsing onto one postganglionic fibre

Question 6

What is divergence?

Answer 6

One preganglionic fibre synapsing onto several postganglionic fibres

Question 7

What type of receptors does Acetylcholine work on?

Answer 7

Cholinergic - nicotinic or muscarinic

Question 8

What type of receptor does Noradrenaline work on?

Answer 8

Adrenergic - alpha and beta receptors

Question 9

What do preganglionic fibres release during sympathetic nervous system and what receptor does it act on?

Answer 9

Acetylcholine on Nicotinic receptors

Question 10

What do postganglionic fibres release and what receptor do they act on during sympathetic system?

Answer 10

Noradrenaline on alpha or beta receptors

Question 11

What cells have no axons but release adrenaline and noradrenaline into the blood?

Answer 11

Postganglionic cells of the adrenal medulla

Question 12

What do preganglionic fibres release and what receptors do they act on during the parasympathetic system?

Answer 12

Acetylcholine on nicotinic receptors.

Question 13

What do postganglionic fibres release and what receptors do they act on during parasympathetic system?

Answer 13

Acetylcholine on muscarinic receptors

Question 14

Give some effects that the sympathetic system produces?

Answer 14

Airways dilate
Heart beats faster
Heart beats stronger
Blood goes to muscle
Gut motility decreases
Gut enzyme secretion inhibited
Stored energy is released
Pupils dilate
Eyes focus far away
Hair stands on end
Mouth gets dry

Question 15

Give some effects the parasympathetic system produces?

Answer 15

Airways constrict
Heart beats slower
Heart beats weaker
Blood goes to gut
Gut motility increases
Gut enzyme secretion is stimulated 
Energy is stored
Pupils construct
Eyes focus close up
Hair lies flat
Mouth starts drooling

Question 16

What receptors relax smooth muscle?

Answer 16

Beta -2

Question 17

What receptors contract smooth muscle?

Answer 17

Alpha -1

Question 18

Name the beta -2 agonist that dilates airways but does not affect the heart?

Answer 18

Salbutamol

Question 19

What does the parasympathetic system do to blood vessels?

Answer 19

Usually has no effect

Question 20

Give an example of single innervation?

Answer 20

Only the sympathetic system acts on energy stores, the parasympathetic system has no effect

Question 21

Give an example of dual innervation with non-antagonistic actions?

Answer 21

Sympathetic system stimulates thick secretions from salivary glands that are rich in enzymes.

The parasympathetic system also stimulates salivary secretion but it produces a watery secretion.

Question 22

Give an example of dual innervation with complementary effects?

Answer 22

Sympathetic system contracts smooth muscle in reproductive tract and causes ejaculation.

Parasympathetic system relaxes smooth muscle in reproductive tract and causes erection.

Question 23

What controls all of these responses?

Answer 23

Autonomic reflexes
Eg baroreceptor reflex detects blood pressure.

Central control via hypothalamus

Question 24

Describe the process of synaptic transmission?

Answer 24

Synthesis and packaging of transmitter into vesicles

Na+ action potential invaded terminal

Activates voltage gated Ca2+ channels

Triggers exocytosis of vesicles

Transmitter diffuses across cleft and binds to postsynaptic receptors

Pre-synaptic autoreceptors inhibit further transmitter release.

Transmitter is inactivated by uptake into glia or neurones

Transmitter is metabolised

Question 25

At a somatic synapse what drug can be used to inhibit choline transporters?

Answer 25

Hemicholinium

Question 26

At a somatic synapse what drug can be used to Block voltage gated Ca2+ channels?

Answer 26

Black widow spider venom.

Question 27

What drugs can block vesicle fusion at somatic synapses?

Answer 27

Botulinium toxins.

Question 28

Give an example of a non-depolarising nicotinic receptor blocker at somatic synapses?

Answer 28

D-tubocurarine.

Question 29

What drug could be used to prolong the AP at somatic synapses?

Answer 29

3,4-aminopyridine.

Question 30

What drug blocks acetylcholinesterase at somatic synapses?

Answer 30

Eserine.

Question 31

What are anti-cholinesterases used for clinically?

Answer 31

Treating myasthenic syndromes. Reversing action of non-depolarising blockers. Countering botulinum poisoning.

Question 32

What blocks ACh activated channels in ganglionic transmission?

Answer 32

Hexamethoneum.

Question 33

What is a non-depolarising nicotinic receptor blocker of the ganglionic transmission?

Answer 33

Mecylamine.

Question 34

What is a depolarising nicotinic receptor blocker of ganglionic transmission?

Answer 34

Suxamethoneum.

Question 35

How could you increase transmission at ganglionic synapses of autonomic pathways?

Answer 35

Activate nicotinic receptors (eg nicotine, is more potent at ganglia than NMJ, N1>N2 receptors).

Question 36

What are the potential sites of action at post-ganglionic parasympathetic synapses?

Answer 36

Muscarinic receptor antagonists (eg atropine). | Muscarinic receptor agonists (eg carbachol, pilocarpine).

Question 37

What do muscarinic agonists do?

Answer 37

Mimic the effect of the parasympathetic system.

Question 38

What do muscarinic antagonists do?

Answer 38

Block effects of the parasympathetic system.

Question 39

What drugs will block the enzymes that produce NA at post-ganglionic sympathetic synapses?

Answer 39

Carbidopa.

Question 40

Give an example of a drug that blocks the transporter that fills the vesicles with NA at post-ganglionic sympathetic synapses?

Answer 40

Reserpine.

Question 41

What drugs block α or β postsynaptic receptors?

Answer 41

Doxazosin. | Propranolo.

Question 42

What are potential sites for action to make post-ganglionic sympathetic synapses to work better?

Answer 42

Stimulate NA adrenaline release (eg amphetamine). Inhibit uptake into neurones (eg cocaine & tricyclic antidepressants) or glia (eg phenoxybenzamine). Activate postsynaptic receptors (eg phenylephrine and salbutamol).