M&R Session 11

Question 1

What can altered receptor responsiveness result from?

Answer 1

Change in receptor number
Change in receptor coupling to 2nd messenger
Change in availability of 2nd messenger
Change in cell responsiveness

Question 2

Which changes causing altered receptor responsiveness are seen clinically?

Answer 2

Change in receptor number

Change in receptor coupling to 2nd messenger

Question 3

How does suprasensitivity arise?

Answer 3

Agonist deprivation

Excessive antagonist exposure

Question 4

What is tachyphylaxis?

Answer 4

Decreased sensitivity of a cell to a ligand

Question 5

How does tachyphylaxis arise?

Answer 5

Excessive exposure to agonist

Question 6

What is activation of mu-opioid receptors associated with?

Answer 6

Analgesia
Sedation
Euphoria

Question 7

What is an example of an endogenous opioid?

Answer 7

Endorphins

Question 8

When are endogenous opiates released?

Answer 8

Stress

Question 9

How does repeated opioid use cause tachyphylaxis?

Answer 9

Repeated use –> receptors upregulated but amount of 2nd messenger is constant

Question 10

What can be said about the level of opioid required to elicit a response in tachyphylaxis?

Answer 10

Increased

Question 11

Why does a patient perceive pain when opioid levels fall?

Answer 11

Molecule leaves receptor and is less likely to be replaced –> 2nd messenger activity falls

Question 12

What are the typical withdrawal S/S of opiate withdrawal?

Answer 12

Distressing, variable, poorly localised pain
Sweating
Anxiety
Constipation

Question 13

Why is it preferable to use patient administered analgesia with opiate based treatment?

Answer 13

Will be administered irregularly so no tachyphylaxis hence dose will stay low

Question 14

How is clinical opioid withdrawal treated?

Answer 14

Decrease dose of opioid
Substitute w/ a different class of analgesia

Question 15

What is phaechromocytoma?

Answer 15

Tumour of the adrenal medulla

Question 16

What are the S/S of phaeochromocytoma?

Answer 16

Sweating
Tremor
Anxiety
High blood pressure

Question 17

What is the characterising feature of the S/S of phaeochromocytoma?

Answer 17

Intermittent

Question 18

What causes the S/S of phaeochromocytoma?

Answer 18

Intermittent increase of catecholamines causing intermittent overstimulation of the sympathetic nervous system

Question 19

Why does a patient not get less symptomatic over time in phaeochromocytoma even though there is an increase in catecholamine release?

Answer 19

Intermittent release so no receptor regulation or secondary messenger alteration, therefore no tachyphylaxis

Question 20

Do adrenoceptors tend to upregulate?

Answer 20

No

Question 21

In which stage of life does asthma most commonly present?

Answer 21

1st-3rd

Question 22

What is asthma associated with?

Answer 22

FHx of eczema, hayfever and allergies

Question 23

What are the S/S of asthma?

Answer 23

Wheezing

Question 24

What can initiate an asthma attack?

Answer 24

Infection
Allergy
Psychological factors

Question 25

How can bronchoconstriction be caused by the nervous system?

Answer 25

Increased parasympathetic stimulation | Decreased sympathetic stimulation

Question 26

Which receptors are involved in bronchoconstriction caused by increased parasympathetic stimulation?

Answer 26

mAChR

Question 27

Which receptors are involved in bronchoconstriction caused by decreased sympathetic stimulation?

Answer 27

Beta-adrenoceptors

Question 28

Treatments for which conditions can elicit asthma?

Answer 28

Hypertension Angina Heart failure

Question 29

What happens to beta-receptors in heart failure?

Answer 29

Up-regulated

Question 30

What can a decrease in beta-adrenoceptors in the lungs cause?

Answer 30

Asthma

Question 31

Why is diagnosing an elderly patient with asthma risky?

Answer 31

They can be denied beta-blockers which they might need to treat a cardiac problem which is actually causing the apparent asthma

Question 32

Describe what happens when long term beta-blocker treatment for angina is removed.

Answer 32

Beta-receptors initially upregulated --> withdraw Tx --> receptor number is high so there is increased sympathetic action

Question 33

How is increased age linked to sensitivity to endogenous catecholamines?

Answer 33

Sensitivity is decreased

Question 34

How does the HR responsiveness to exogenous catecholamines vary with age?

Answer 34

Decreases

Question 35

What can happen to the pharmacological efficacy of a long term administered drug with increasing age?

Answer 35

It can potentially become excess

Question 36

What can excess pharmacological efficacy in long-term beta-blocker treatment cause?

Answer 36

Symptomatic bradycardia

Question 37

What does the interaction between a ligand and receptor depend on?

Answer 37

Molecular size Molecular shape Electrical charge