Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmacology & Therapeutics Y2 > Cholinomimetics > Flashcards

Cholinomimetics Flashcards

1
Q

What are cholinomimetics

A

Drugs that mimic the action of ACh

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the reuptake mechanism of ACh

A

It doesn’t get reuptaken

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the synthesis, excretion, metabolism of ACh

A

Acetyl CoA and choline is converted to ACh and CoA. ACh is packaged into vesicles and secreted upon the arrival of an action potential. in the synapse it activates its receptor and then is broken down into choline and acetate by acetylcholinesterase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What enzyme breaks down ACh and what are the products

A

Acetylcholinesterase, choline and acetate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is ACh synthesised from

A

Choline and acetyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What enzyme synthesises ACh, what’s the other product

A

choline acetyltransferase, CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What types of receptor ACh stimulate, nicotinic or muscarinic

A

Both

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What drug is commonly used as a muscarinic antagonist

A

atropine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

which branch of the NS corresponds with muscarinic stimulation

A

parasympathetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what can happen if you administer a large dose of ACh after using atropine

A

you stimulate nicotinic receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which muscarinic receptors are excitatory vs inhibitory

A

All 5 except M2 on the heart are excitatory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

where are M2 receptors found

A

Heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where are M1 receptors found (3)

A

salivary glands, stomach and CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where are M3 receptors found (4)

A

Salivary glands, bronchial/visceral smooth muscle, sweat glands, eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What types of muscarinic receptors are found at: Salivary glands, bronchial/visceral smooth muscle, sweat glands, eye

A

M3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What types of muscarinic receptors are found at: the heart

A

M2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What types of muscarinic receptors are found at: salivary glands, stomach and CNS

A

M1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are special about M2 receptors

A

Inhibitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are special about the hearts muscarinic receptors

A

Inhibitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where are M4 receptors found

A

CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where are M5 receptors found

A

CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What type of receptor are muscarinic receptors

A

Type 2 G protein couples

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What type of G protein receptors are M1, 3 and 5

A

Gq proteins linked to IP3 and DAG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What type of G protein receptors are M2 and 4

A

Gi proteins and linked to cAMP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Which muscarinic receptors are Gq proteins

A

M1, 3 and 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Which muscarinic receptors are Gi proteins

A

M2 and 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Which muscarinic receptors are IP3 and DAG linked

A

1, 3 and 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Which muscarinic receptors are linked to cAMP

A

2 and 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

cAMP is which type of G protein?

A

Gi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

IP3 and DAG is which type of G protein?

A

Gq

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Gq protein uses which second messenger?

A

IP3 and DAG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Gi protein uses which second messenger?

A

cAMP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What type of receptors are nicotinic receptors?

A

Type 1 gated ion channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Which types of muscarinic receptor is found in the CNS

A

1, 4 and 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

How many subunits on a nicotinic receptor and what are they called?

A

5 subunits, known as alpha beta gamma delta and epsilon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What determines the ligand binding properties of a nicotinic receptor

A

the subunit combination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Which branch of the NS uses nicotinic receptors

A

Both

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the subunit combination of nicotinic receptors in muscle

A

2alpha, beta, delta, epsilon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the subunit combination of nicotinic receptors in ganglions

A

2alpha 3beta

40
Q

2alpha 3beta is the nicotinic subunit combination for where

A

ganglions

41
Q

2alpha, beta, delta, epsilon is the nicotinic subunit combination for where

A

Muscle

42
Q

Where are ACh effects more potent, muscarinic or nicotinic receptors

A

Muscarinic

43
Q

What type of muscarinic receptors are found in the eye

A

M3

44
Q

What does contraction of the sphincter pupillae do

A

constricts the pupil and improves drainage of intraocular fluid by opening up pathway for aqueous humour, allowing the Canal of Schlemm to drain aqueous humour and reducing intraocular pressure

45
Q

What does contraction of the ciliary muscle do

A

Accommodates for near vision by bulging the pupil

46
Q

What’re the muscarinic effects of the eye (3)

A

Contraction of the sphincter pupillae, ciliary muscle and lacrimation

47
Q

How does stimulation of the muscarinic receptor reduce intraocular pressure

A

Opening up the pathway for aqueous humour and allowing drainage via the canals of Schlemm

48
Q

What effect does muscarinic stimulation have on the heart

A

reduction in cAMP and decreased cardiac output and heart rate

49
Q

What effects does muscarinic stimulation have on smooth muscle

A

Stimulates NO release which induces vascular smooth muscle relaxation leading to a lower TPR

50
Q

What effects does muscarinic stimulation have on the CVS system

A

Decreased heart rate (M2) (bradycardia).
Decreased cardiac output (due to decreased atrial contraction).
Vasodilation (stimulation of NO production).
All of this combined leads to a sharp drop in BP.

51
Q

What effects does muscarinic stimulation have on non-vascular smooth muscle (3)

A

Lung: bronchoconstriction.
Gut: increased peristalsis (motility).
Bladder: increased bladder emptying

52
Q

What effects does muscarinic stimulation have on the exocrine glands

A

Salivation.
Increased bronchial secretions.
Increased gastro-intestinal secretions (including gastric HCl production).
Increased sweating (SNS-mediated).

53
Q

Summarise the effects of muscarinic stimulation (7)

A 
Decreased heart rate.
Decreased blood pressure.
Increased sweating.
Difficulty breathing.
Bladder contraction.
Gastrointestinal pain.
Increased salivation and tears
54
Q

Where are M2 receptors found in the heart

A

Atria and nodes

55
Q

What type of muscarinic receptor is found on vascular endothelial cells

A

M3

56
Q

Does the vasculature have a direct parasympathetic stimulation?

A

No

57
Q

How does muscarinic stimulation result in a lower blood pressure

A

ACh acts on vascular endothelial cells to stimulate NO release via M3 AChR.
NO induces vascular smooth muscle relaxation, resulting in a decrease in TPR.

58
Q

What is the difference in reaction to muscarinic stimulation by vascular and non-muscular smooth muscle

A

Smooth muscle that does have parasympathetic innervation responds in the opposite way to vascular muscle – it contracts

59
Q

2 types of cholinomimetics

A

Choline esters and alkaloids

60
Q

Example of a choline ester?

A

Bethanechol

61
Q

Example of an alkaloid?

A

Pilocarpine

62
Q

Give an example of a selective M3 agonist

A

Bethanechol

63
Q

Metabolism of bethanechol?

A

Resistant to degradation as it is not broken down by AChesterase, half-life of 3/4 hours

64
Q

What does bethanechol act on

A

M3

65
Q

Side effects of bethanechol (5)

A

sweating, impaired vision, bradycardia, hypotension and respiratory difficulty

66
Q

Give an example of a non-selective muscarinic agonist

A

Pilocarpine

67
Q

what is betanechol used for

A

To assist bladder emptying and gastric motility

68
Q

How much access to the brain does bethanechol have and why

A

Limited as it is not lipid soluble

69
Q

How lipid soluble is bethanechol

A

Not very

70
Q

How lipid soluble is pilocarpine

A

Good lipid solubility

71
Q

Half life of pilocarpine?

A

3/4 hours

72
Q

What is the use of pilocarpine? Why is this what it is ideal for

A

Local treatment for glaucoma, its lipid solubility allows it to readily pass through the cornea

73
Q

side effects of pilocarpine? (6)

A

Blurred vision, sweating, gastro-intestinal disturbance and pain, hypotension, respiratory distress

74
Q

Two types of cholinesterase enzymes?

A

Acetylcholinesterase and butyrylcholinesterase

75
Q

Where is AChesterase found

A

All cholinergic synapses

76
Q

What is the speed and selectivity of AChesterase

A

Very rapid and highly selective for ACh

77
Q

Where is butyrylcholinesterase found

A

In plasma and most tissues but not cholinergic synapses

78
Q

what is specificity of butyrylcholinesterase

A

Broad specificity so it hydrolyses other esters

79
Q

What is the main reason for a low plasma ACh

A

Butyrylesterase

80
Q

What are the 2 types of anticholinesterases

A

Reversible and irreversible

81
Q

What is bethanechol an example of (2)

A

Choline ester, selective M3 agonist

82
Q

What is pilocarpine an example of (2)

A

Alkaloid, non-selective muscarinic agonist

83
Q

Example of a reversible anticholinesterase

A

Physostigmine

84
Q

Example of an irreversible anticholinesterase

A

Ecothiopate

85
Q

What does a low dose of an anticholinesterase do

A

Enhanced muscarinic activity

86
Q

What does a moderate dose of anticholinesterase do (2)

A

Further enhanced msucarinic activity and increased transmission at all autonomic ganglia

87
Q

What does high dose of anticholinesterase do

A

Toxic, depolarising block at all autonomic ganglia and NMJ

88
Q

How does a reversible anticholinesterase work

A

Competes with ACh for active site of the cholinesterase. They donate a carbamyl group to the enzyme, blocking the active site and preventing ACh from binding. The carbamyl group is removed by slow hydrolysis (mins rather than msecs) and this increases the duration of ACh activity in the synapse

89
Q

What is physostigmine an example of

A

Reversible anticholinesterase

90
Q

What is ecothiopate an example of

A

Irreversible anticholinesterase

91
Q

How does an irreversible anti cholinesterase work

A

organophosphate compounds. They rapidly phosphorylate the enzyme active site, leaving a large blocking group. This is stable and resistant to hydrolysis, meaning recovery may take weeks as it is mostly done with the production of new enzymes. An example is ecothiopate

92
Q

What is physostigmine used for

A

acts at the postganglionic parasympathetic synapse and has a half life of around 30 mins. It is used in the treatment of glaucoma and helps to drain intraocular fluid. It can also be used to treat atropine poisoning.

93
Q

What is ecothiopate used for

A

Used as eye drops in the treatment of glaucoma, acting to increase intraocular fluid drainage with a prolonged duration of action

94
Q

What must be considered when using non-polar anticholinesterases

A

Effect on the CNS as they can cross the BBB.
Low doses can cause excitation with possibility of convulsions and high doses can result in unconsciousness, respiratory depression and even death

95
Q

What drug class do organophosphates belong to

A

Irreversible anticholinesterases

96
Q

how do you treat organophosphate poisoning

A

the use of atropine I.V., artificial respiration and pralidoxime I.V.. Pralidoxime can reverse an irreversible anticholinesterase if given within a few hours of phosphorylation, otherwise the phosphorylated enzyme ‘ages’ and becomes fully irreversibl

97
Q

What drug is used to treat organophosphate poisoning

A

Pralidoxime

Pharmacology & Therapeutics Y2 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions