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Pharmacology Y2 > Sympathetic Nervous System > Flashcards

Sympathetic Nervous System Flashcards

1
Q

Define the word ‘gating’ in terms of activation on an agonist

A

This is the reaction where the complex of the agonist and receptor become active

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2
Q

When does affinity occur in the activation of a drug?

A

This is when the agonist and receptor bind to each other

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3
Q

When does efficacy occur in the activation of a drug?

A

This is when the complex of the agonist and receptor become activated

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4
Q

Do modulators act at the same binding site as the agonist?

A

No, they act at an allosteric binding site

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5
Q

What is the function of modulators?

A

They can either increase or decrease the effect of the agonist, so a lower concentration of the drug is required to achieve the drug result

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6
Q

What is a reversible competitive antagonist?

A

When bound to the receptor it prevents the agonist from binding to the receptor

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7
Q

What happens if you increase the concentration of the agonist to a reversible competitive antagonist?

A

It can overcome the effect of the antagonist as the bonds formed by the antagonist are not permanent

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8
Q

What is an irreversible competitive antagonist?

A

When bound to the receptor it prevents the agonist binding, but bonds covalently so limits the maximum efficacy that can be reached

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9
Q

What is a non competitive antagonist?

A

When bound to receptor covalently it prevents the agonist from binding, however binds to an allosteric site on the receptor

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10
Q

What does selective mean in terms of antagonists/agonists?

A

Means that the drug affects that specific receptor in a specific cell population, and will have a stronger effect there rather than other sites

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11
Q

What does non selective mean in terms of antagonists/agonists?

A

Means that the drug will nit distinguish between drug sites and the receptor it binds to, will affects multiple sites in the body

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12
Q

Which adrenoreceptors are excitatory?

A

Alpha 1
Beta 1
Beta 2

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13
Q

Which adrenoreceptors are inhibitory?

A

Alpha 2
Beta 3

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14
Q

Name 2 non selective alpha receptor antagonists

A

Phenoxybenzamine
Phentolamine

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15
Q

Is phenoxybenzamine competitive or non competitive?

A

It is a non competitive antagonist

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16
Q

Is phentolamine competitive or non competitive?

A

Competitive, reversible

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17
Q

Which receptors does phenoxybenzamine and phentolamine affect?

A

Alpha 1
Alpha 2

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18
Q

What happens to blood pressure when adrenaline is added?

A

Initially increases due to activation of alpha 1+ beta 1 receptors, then decreases back to normal due to baroreceptor reflex

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19
Q

What happens to blood pressure when phentolamine is added?

A

Initially decreases due to inhibition on alpha 1 + beta 1 receptors, then increases back to normal due to baroreceptor reflex

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20
Q

What happens to blood pressure when adrenaline is added in the presence of phentolamine?

A

Blood pressure decreases -> adrenaline is much lower due to the competitive antagonism -> low levels of adrenaline activate beta 2 instead of alpha 1 -> beta 2 receptors cause vasodilation, so blood pressure decreases

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21
Q

Name 3 selective alpha 1 antagonists

A

Prazosin
Doxazosin
Tamulosin

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22
Q

Name 3 selective alpha 2 antagonists

A

Yohimbine
Idazoxan
Atipamezole

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23
Q

How do alpha 2 antagonists result in antidepressant effects?

A

Blocking alpha 2 prevents noradrenaline reuptake form the synapse -> more neurotransmitter in the synapse can result in antidepressant effects

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24
Q

How do alpha 1 antaognists result in postural hypotension(venous pooling)?

A

Blocked baroreceptor reflex -> sympathetic nervous system is not able to increase heart rate fast enough through vasoconstriction or sympathetic drive when standing up -> results in venous pooling

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25
How do alpha 1 antagonists result in nasal stuffiness?
Causes dilation of blood vessels in nasal passage -> narrows the airways
26
How do alpha 1 antagonists result in miosis (constriction of the pupil)?
Radial muscle in eye dilates with alpha 1 activation -> antagonist for alpha 1 will result in constriction of the pupil
27
What is the baroreceptor reflex response to the blood pressure falling due to alpha 1 antagonists?
Baroreceptor reflex can only affect sympathetic drive not vasculature -> activates beta 1 -> tachycardia -> increases release of renin for RAAS -> increased reabsorption of sodium and water -> oedema/weight gain
28
How are alpha adrenoreceptor antagonists used to treat hypertension?
Alpha 1 antagonists prevent noradrenaline or adrenaline from binding to alpha 1 receptors on vasculature -> vasodilation -> lowered blood pressure
29
How are alpha adrenoreceptor antagonists used to treat benign prostatic hyperplasia?
Alpha 1 antagonists prevents noradrenaline or adrenaline from binding to the smooth muscle of the prostate -> dilation of the smooth muscle -> allows urethra to open to empty bladder
30
Which selective alpha 1 antagonist has a high affinity to alpha 1 receptors on the prostate?
Tamulosin
31
If an antagonist has a high affinity for the receptor, does it require a high or low dosage?
High affinity drugs require a lower dosage for the wanted drug result
32
If an antagonist has a low affinity for the receptor, does it require a high or low dosage?
Low affinity drugs require a higher dosage for the wanted drug result
33
Which selective alpha 1 antagonist has a low affinity to alpha 1 receptors on the prostate?
Prazosin
34
What contra indication could occur with a high dosage of a alpha 1 antagonist?
Blood pressure could also lower which could be dangerous
35
Name 3 selective beta 1 antagonists
Atenolol Bisoprolol Metoprolol
36
Name 2 non selective beta 1 antagonists
Propanolol Sotalol
37
Propanolol also blocks beta 2 receptors aswell as beta 1. What are the contraindications of this?
Blocking beta 2 receptors will also prevent bronchodilation of the smooth muscle in trachea, therefore can be dangerous for people with asthma.
38
Define intrinsic sympathomimetic activity
Beta blockers that can stimulater agonistic and antagonist effects of adrenaline and noradrenaline
39
Do beta blockers with intrinsic sympathomimetic activity have agonistic effects at low concentrations?
No, only at high concentrations, therefore is not a partial agonist
40
Outline where a beta blocker with intrinsic sympathomimetic activity would be used
The beta blocker could be used to cause vasodilation and bradycardia, but if you wanted to also stimulate the heart the intrinsic sympathomimetic activity would work to do this
41
Name 2 beta blockers with intrinsic sympathomimetic activity
Pindolol Oxyprenolol
42
What receptors can a vasodilation beta blocker act on?
Beta receptors Alpha 1 receptors
43
Name 2 vasodilation beta blockers that act on beta and alpha 1 receptors
Carvedilol Labetalol
43
Name 2 vasodilation beta blockers that act on beta and alpha 1 receptors
Carvedilol Labetalol
44
What is the effect of carvedilol binding to beta receptors?
Reduced heart rate and contractility
45
What is the effect of carvedilol binding to alpha 1 receptors?
Reduced peripheral resistance Decreased blood pressure
46
Does the baroreceptor reflex occur when carvedilol is given?
No - the response of baroreceptor reflex to vasodilation is to increase heart rate, however it cannot dp this as carvedilol also acts of the beta 1 receptors of the heart, so no compensation occurs
47
Name a drug that uses nitric oxide to cause vasodilation?
Nebivolol
48
How does nevibolol cause vasodilation?
Activates beta 3 Inactivates beta 1
49
How does activating beta 3 receptors result in vasodilation?
Beta 3 stimulation of the myocardium releases NO from the endothelium of the myocardium. NO causes vasodilation, reducing fibrosis and hypertrophy.
50
List 5 conditions that beta adrenoreceptor antagonists are a therapeutic use against
Congestive heart failure Angina Hypertension Myocardial infarction Arrhythmias
51
How do beta adrenoreceptor antagonists help angina?
Reduces heart workload Reduced pain
52
How do beta adrenoreceptor antagonists help hypertension?
Reduced cardiac output Reduced renin release (reduced angiotensin 2 release) Reduced water retention Reduced blood pressure
53
How do beta adrenoreceptor antagonists help myocardial infarction?
Reduced sympathetic stimulation from the brain Reduced blood pressure
53
How do beta adrenoreceptor antagonists help myocardial infarction?
Reduced sympathetic stimulation from the brain Reduced blood pressure
54
How can beta adrenoreceptor antagonists help thyrotoxicosis?
Decreased thyroid hormone release Decreased sympathetic stimulation
55
How can beta adrenoreceptor antagonists help glaucoma?
Blocks beta 2 receptors on the ciliary body which reduces production of aqueous fluid, therefore reducing the intraocular pressure
56
Lipid soluble drugs have a _______ half life
Shorter
57
_____ soluble drugs have a longer half life
Water
58
Lipid soluble drugs are metabolised by the _____
Liver
59
_____ soluble drugs are excreted by the kidney
Water
60
What does it mean is a beta blocker has 'spontaneous activity'?
Nothing needs to be bound to it in order to activate it, it can be activated on its own without an agonist
61
Can a neutral, normal antagonist block the receptor even when an agonist is not present?
No, the agonist has to be present for the antagonist to block the action of the receptor
62
What type of beta blocker can prevent spontaneous activity from occurring even when an agonist is not present?
Inverse agonist
62
What type of beta blocker can prevent spontaneous activity from occurring even when an agonist is not present?
Inverse agonist
63
Describe the action of inverse agonists
Antagonists that, when bound, prevent the agonist from binding but also stop the receptor from spontaneously going into the active state when the agonist is not present
64
Name an inverse agonist
Metaprolol
65
List 5 unwanted side effects of beta blockers
Fatigue Bradycardia Cold extremities Hypoglycaemia Sleep disturbance/nightmares
66
How can beta blockers cause hypoglycaemia?
Beta 2 receptors on the liver stimulate the release of glucose, so when these receptors are blocked the body cannot increase the blood glucose levels fast enough for the bodys need
67
What disease can be caused by prolonged hypoglycaemia?
Insulin resistance and type 2 diabetes
68
How can hypoglycaemia caused by beta blockers lead to diabetes?
Reaction to hypoglycaemia is to increase beta stimulation to release more glucose from the liver, however this will exacerbate the hypoglycaemia
69
What affect do beta blockers have on blood triglycerides and HDL?
They increase the blood triglycerides and decrease levels of HDL (good thing)
70
What affect do alpha 1 antagonists have on blood triglycerides and HDL?
They reduce blood triglycerides and increase levels of HDL (and decrease LDL, bad thing)
71
Name 2 beta blockers that all have an alpha 1 antagonistic effect?
Carvedilol Labetalol
71
Name 2 beta blockers that all have an alpha 1 antagonistic effect?
Carvedilol Labetalol
72
Only when the Gs receptor is ______________, it allows arresting to bind
Phosphorylated
73
What happens when arrestin is bound to a Gs receptor?
It results in desensitisation and inactivation of the Gs receptor
74
Name 2 beta blockers that stimulate the phosphorylation and arrestin pathway of blocking receptors
Carvedilol Nebivolol
75
Why would the arrestin pathway be favoured over blocking the receptor sites for adrenaline and noradrenaline?
It reduces the levels of cAMP and Ca2+ influxes during heart failure
76
Blockage of adrenoreceptors can be caused by inhibition of s________ and s______ of neurotransmitter
Synthesis Storage
77
Name 3 drugs that are used in the blockage of synthesis of adrenaline and noradrenaline
Alpha methyltyrosine Alpha methyl DOPA Disulfiram
77
Name 3 drugs that are used in the blockage of synthesis of adrenaline and noradrenaline
Alpha methyltyrosine Alpha methyl DOPA Disulfiram
78
What is the mechanism of alpha methyl tyrosine?
It blocks the tyrosine hydroxylase enzyme in the pathway that forms adrenaline and noradrenaline
79
What is the mechanism of alpha methyl DOPA?
It is an analogue of L-DOPA, so is substitutes into the pathway and eventually forms alpha methyl noradrenaline
80
How does alpha methyl noradrenaline reduce sympathetic outflow?
It is selective for alpha 2, so does not cause vasoconstriction, and activation of more alpha 2 receptors reduces sympathetic outflow from brain stem
81
Which enzyme in production of adrenaline and noradrenaline does disulfiram block?
It blocks dopamine beta hydroxylase so prevents dopamine becoming noradrenaline or adrenaline
82
Name a drug used to prevent noradrenaline reuptake into the presynaptic vesicle
Reserpine
83
Which receptor on the pre synaptic vesicles does reserpine block?
VMAT2
84
Why is reserpine effective?
Prevents noradrenaline coming back to pre synaptic knob so I cannot be released again into the synapse
85
How does blockage of alpha 2 receptors affect noradrenaline release from the presynaptic membrane?
Blocking the alpha 2 receptors means that there is no detection of noradrenaline in the synapse, therefore more noradrenaline is released from the presynaptic membrane
86
Are the blood vessels in the nasal passage determined by alpha 1 or beta 2?
Their vasoconstriction/vasodilation relies on the stimulation of alpha 1 receptors
87
Which receptors are involved in angina?
Angina is to do with the constriction of coronary blood vessels, which is caused by alpha 1 receptors

Pharmacology Y2 (9 decks)

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