S8 - ANS

Question 1

What does the ANS control?

Answer 1

All involuntary functions

Question 2

Is the ANS afferent or efferent?

Answer 2

Efferent (regulated by afferent input)

Question 3

What are the differences between the sympathetic and parasympathetic nervous systems?

Answer 3

Parasympathetic - rest and digest - regulates basal activities like digestion

Sympathetic - flight or flight - increases heart rate, etc.

Question 4

What are the divisions of the brain stem and spinal cord?

Answer 4

Medullary
Cranial
Thoracic
Lumbar
Sacral

Question 5

Where does the sympathetic emerge from?

Answer 5

Thoracic and lumbar regions

Question 6

Where does the parasympathetic emerge from?

Answer 6

The medullary and sacral regions

Question 7

Are pre- or post-ganglionic neurones usually myelinated?

Answer 7

Pre-ganglion is neurons

Question 8

Where are ganglia located in the parasympathetic and sympathetic?

Answer 8

Parasympathetic - within innervated tissues

Sympathetic - paravertebral chain (close to spinal cord)

Question 9

What type of receptors are at pre-ganglionic neurons (to post-ganglionic neuron)?

Answer 9

Nicotinic ACh receptors (cholinergic) - ligand gated

Question 10

What type of receptors are at parasympathetic post-ganglionic neurons (to tissue)?

Answer 10

Muscarinic ACh receptors (cholinergic) - GPCRs

Question 11

What type of receptors are at sympathetic post-ganglionic neurons (to tissue)?

Answer 11

Adrenoreceptors - noradrenergic - alpha and beta adrenoreceptors

Question 12

What are other NTs?

Answer 12

ATP, nitric oxide, 5HT/serotonin, neuropeptides

Question 13

What is the enteric nervous system?

Answer 13

Controls the GI system - capable of operating independently of CNS - has many neurons

Question 14

Where is adrenaline/noradrenaline released from?

Answer 14

Adrenal gland (adrenal medulla)

Chromaffin cells (in the adrenal medulla) - release adrenaline into blood stream due to stimulation by the preganglionic neuron (NT - ACh)

Question 15

What receptor type stimulated skeletal muscle (in the somatic efferent system)?

Answer 15

nAChR

Question 16

What receptor types stimulate blood vessels, etc (in the sympathetic system)?

Answer 16

Pre - nAChR

Post - NA receptor

Question 17

What receptor types stimulate salivary glands, etc. (In the parasympathetic system)?

Answer 17

Pre - nAChR

Post - mAChR

Question 18

What receptors stimulate sweat glands (in the sympathetic system)?

Answer 18

Pre - nAChR

Post - mAChR

Question 19

What receptor types stimulate parasympathetic release of ACh?

Answer 19

Muscarinic receptors

Question 20

What receptor types stimulate sympathetic release of noradrenaline?

Answer 20

Alpha and beta receptors

Question 21

Which receptor is targeted to treat asthma?

Answer 21

Beta-2 receptors

Question 22

What are the common sites of drug action in neurotransmission?

Answer 22

NT degradation
NT interaction with post-synaptic receptors
NT inactivation
NT reuptake
NT interaction with pre-synaptic receptors

Question 23

How is ACh synthesised?

How is ACh degraded?

Answer 23

Acetyl CoA + choline —> acetylcholine + CoA
Using choline acetyltransferase

ACh —> acetate (metabolised) + choline (recycled)
Using acetylcholine esterase

Question 24

Give examples of mAChR agonists/antagonists.

Answer 24

1. Tolterodine (antagonist) - used to treat an overactive bladder
2. Pilocarpine (agonist) - treats glaucoma
3. Bethanechol (agonist) - stimulates bladder emptying
4. Ipratropium and tiotropium (antagonists) - treat asthma and COPD

Question 25

What happens if a drug isn’t selective enough?

Answer 25

It leads to unwanted autonomic side effects that limit their usage.

Question 26

What happens if a mAChR agonist drug is non-selective?

Answer 26

1. Reduced heart rate/cardiac output (heart) 2. Increased bronchoconstriction/GI tract peristalsis (smooth muscle) 3. Increased sweating/salivation (exocrine glands)

Question 27

What does SLUDGE stand for?

Answer 27

``` Salivation Lacrimation Urination Defecation Gastrointestinal upset Emesis ```

Question 28

What is SLUDGE indicative of?

Answer 28

A change in the parasympathetic nervous system (over- or under-active)

Question 29

When does SLUDGE syndrome often occur?

Answer 29

1. Drug overdose 2. Ingestion of magic mushrooms 3. Exposure to organophosphates or nerve gases 3 changes AChE so can’t break down ACh

Question 30

What usually causes SLUDGE symptoms?

Answer 30

Over-stimulation of mAChRs in parasympathetic nervous system

Question 31

How can you treat SLUDGE?

Answer 31

Treat with atropine, pralidoxime - anti-cholinergic agents

Question 32

What are two examples of drugs that can enhance the actions of endogenously released ACh?

Answer 32

1. Pyridostigmine - acetylcholine esterase inhibitor to treat myasthenia gravis 2. Donepezil - treats Alzheimer’s (AChE inhibitor)

Question 33

What do post-ganglionic neurons possess (in terms of branching)?

Answer 33

Varicosities - specialised site for Ca2+ dependent noradrenaline release

Question 34

Where is noradrenaline converted to adrenaline?

Answer 34

In the adrenal medulla

Question 35

After Ca2+ dependent exocytotic release of NA at varicosities, what happens?

Answer 35

NA diffuses across synaptic cleft and interacts with adrenoreceptors in post-synaptic membrane Or it interacts with pre-synaptic adrenoreceptors to regulate processes in the nerve terminal e.g. NA release

Question 36

How is NA uptaken by the pre-synaptic terminal?

Answer 36

1. Na+ dependent, high affinity transporters | 2. Any not taken up by the 1st way is taken up by lower affinity, non-neuronal mechanisms

Question 37

What two enzymes metabolise NA that isn’t taken up by vesicles?

Answer 37

``` Monamine oxidase (MAO) Catechol-O-methyltransferase (COMT) ```

Question 38

What is the process of NA synthesis?

Answer 38

Tyrosine —> DOPA —> Dopamine —> NA

Question 39

What is an example of a beta-2 adrenoreceptor-selective agonist?

Answer 39

Salbutamol - used in asthama to oppose bronchoconstriction.

Question 40

What is the benefit of a selective beta-2 adrenoceptor used for asthma?

Answer 40

Limits possible cardiovascular side effects e.g. positive inotropy

Question 41

What is an example of an alpha-1 adrenoceptor selective antagonist?

Answer 41

Doxazosin - used to treat hypertension

Question 42

What is an example of an beta-1 adrenoceptor selective antagonist?

Answer 42

Atenolol - used to treat hypertension