ANS effectors

Question 1

Agonist activation of the parasympathetic nervous system has what effect on the salivary glands, heart, airways, GI tract and bladder respectively?

Answer 1

Salivation, reduced heartrate, bronchoconstriction and mucus secretion, increased motility and secretion, relaxation of sphincter and micturition.

Question 2

What nerve carries parasympathetic innervation to the heart?

Answer 2

Vagus (X)

Question 3

Which part of the ANS has the longest pre-ganglionic neuron?

Answer 3

Parasympathetic

Question 4

True or false: the sympathetic postganglionic neurons are longer than parasympathetic

Answer 4

True

Question 5

What are the acetylcholine receptors on the proximal end of the post-ganglionic neuron in the ganglion called?

Answer 5

Nicotinic

Question 6

Where are the muscarinic acetylcholine receptors located?

Answer 6

At the target organ.

Question 7

What type of receptors are nicotinic?

Answer 7

ligand-gated ion channel

Question 8

What happens to acetylcholine after it has bound to muscarinic receptors at the target organ?

Answer 8

It is hydrolysed by acetylcholine-esterase and choline is transported back into the post-ganglionic nerve to be remade into acetylcholine.

Question 9

What type of receptors are muscarinic?

Answer 9

G-protein coupled

Question 10

Where are the G-proteins bonded in the receptor?

Answer 10

To the intracellular surface of the receptor

Question 11

What are the three types of G protein found in GPCRs?

Answer 11

Gq, Gs and Gi

Question 12

Describe the sequence of events after acetylcholine has stimulated a GPCR with a Gq protein at the target organ?

Answer 12

Seven subunits of the extracellular receptor change shape, releasing the intracellular Gq protein. This activates phospholipase C which converts PIP2 to IP3. IP3 binds to receptors on the sarcoplasmic reticulum which then releases calcium.

Question 13

What are the muscarinic antagonists?

Answer 13

aTROPine, ipraTROPium, tioTROPium

Question 14

Why does atropine have so many undesired side effects?

Answer 14

It is uncharged, so moves across membranes easily and can cause effects on muscarinic receptors all over the body.

Question 15

What is the difference between ipratropium and tiotropium?

Answer 15

ipratropium is fast-acting for a short duration, tiotropium is slow-acting over a long duration.

Question 16

What type of receptors would you find at the proximal end of the post-ganglionic fibres in the sympathetic nerve system?

Answer 16

Nicotinic

Question 17

What part of the ANS are adrenergic receptors found, where specifically are they?

Answer 17

Sympathetic, on the target organ

Question 18

What neurotransmitter stimulates adrenergic receptors?

Answer 18

Noradrenaline

Question 19

What tissues receive sympathetic innervation from acetylcholine instead of noradrenaline?

Answer 19

Sweat glands and adrenal medulla

Question 20

What are the subtypes of adrenergic receptors and why are they different?

Answer 20

Alpha-1 and 2, Beta-1 and 2. They react to adrenaline, isoprenaline and noradrenaline differently. Generally, alpha are more reactive to adrenaline and beta are more reactive to isoprenaline.

Question 21

What main type of adrenergic receptors are found in the heart and the lungs respectively?

Answer 21

Beta-1- heart
Beta 2- lungs

Question 22

What type of receptor is an adrenergic receptor?

Answer 22

GPCR (Gs type)

Question 23

What is the signalling molecule in Gs GPCRs?

Answer 23

cAMP

Question 24

An influx of sodium into a cardiac cell has what effect?

Answer 24

Increased rate of contraction

Question 25

An influx of calcium into a cardiac cell has what effect?

Answer 25

Increased force of contraction

Question 26

What type of drug is salbutamol?

Answer 26

Selective Beta-2 agonist

Question 27

What is the difference between salbutamol and salmeterol?

Answer 27

Salmeterol has a longer chain that is resistant to breakdown, so has a longer mechanism of action

Question 28

How id noradrenaline removed from the synapse and what drugs inhibit this?

Answer 28

Via noradrenaline transporter protein, cocaine and amphetamines.

Question 29

What effects can cocaine have on the heart and bladder?

Answer 29

Increase force and rate of heartbeat, decrease micturition.

Question 30

What is a LABA?

Answer 30

Long-acting beta-2 agonists

Question 31

What is the most common side effect of a beta-2 agonist?

Answer 31

Skeletal muscle tremor

Question 32

What is a common side effect of ipratropium and why?

Answer 32

dry mouth, muscarinic antagonist so decreases salivation

Question 33

What is the mechanism of action of theophylline?

Answer 33

Inhibits the enzyme the hydrolyses cAMP, meaning cAMP can trigger MLCK to relax smooth muscle (bronchodilation)

Question 34

What drug class is theophylline in?

Answer 34

Methylxanthines

Question 35

Methylxanthines are in the same chemical class as caffeine, what does this mean for the side-effects of methylxanthines?

Answer 35

CNS stimulation, heart palpitations

Question 36

Name an example of a leukotriene antagonist and it's effects

Answer 36

Montelukast, blocks leukotrienes which are pro-inflammatory mediators, decrease bronchoconstriction, vascular permeability and mucus production

Question 37

Name two corticosteroids

Answer 37

Prednisolone and beclomethasone

Question 38

What is different about the mechanism of action of corticosteroids compared to other respiratory medicines?

Answer 38

Bind to cytoplasmic receptors inside cells, they then alter DNA transcription to decrease the production of pro-inflammatory mediators

Question 39

What are the undesired side effects of corticosteroids?

Answer 39

Adrenal suppression, osteoporosis, Cushing's syndrome, suppression of immune system.

Question 40

What is the most common undesired side effect of inhaled corticosteroids?

Answer 40

Oral thrush

Question 41

Action at what receptors causes the side effect of sedation?

Answer 41

Histamine

Question 42

Action at dopamine receptors causes what side effects?

Answer 42

Sexual dysfunction and breast changes

Question 43

What type of G protein is an adrenergic receptor?

Answer 43

Gs

Question 44

What type of G protein is a muscarinic receptor?

Answer 44

Gq

Question 45

Describe the mechanism of a Gq receptor

Answer 45

Gq activated by acetylcholine -> phospholipase C converts PIP2 to IP3 -> IP3 binds to receptors on sarcoplasmic reticulum -> calcium released -> MLCK activated -> muscle contraction

Question 46

Describe the mechanism of a Gs receptor

Answer 46

Gs activated by noradrenaline -> cAMP activated -> increase in Na influx + activates PKA -> increase Ca influx -> increase in force and rate of muscle contraction