Asthma and Airway Control

Question 1

What is the dominant control of bronchial smooth muscle tone?

Answer 1

parasympathetic cholinergic innervation of airways

Question 2

What does stimulation of bronchial smooth muscle and submucosal glands by post ganglionic fibres cause?

Answer 2

Bronchial smooth muscle contraction
Increased mucus secretion
Overall increased airway resistance

Question 3

Which muscarinic ACh receptor mediates bronchial smooth muscle relaxation?

Answer 3

M3

Question 4

What does stimulation of bronchial smooth muscle by B2 adrenoceptors of the sympathetic division cause?

Answer 4

bronchial smooth muscle relaxation

Question 5

What activates B2 adrenoceptors?

Answer 5

adrenaline released from adrenal gland

Question 6

Does the sympathetic division increase or decrease mucociliary clearance?

Answer 6

Increase

Question 7

Give examples of stimuli which may cause airway obstruction in asthma.

Answer 7

Allergens, exercise, respiratory infections, smoke, dust, pollutants etc

Question 8

Which pathological changes occur in asthma to the smooth muscle in bronchioles?

Answer 8

Increased mass of smooth muscle by hyperplasia and hypertrophy

Question 9

What happens to mucus secretion in asthma?

Answer 9

increases

Question 10

What other pathological changes occur in asthma?

Answer 10

Epithelial damage, interstitial fluid (oedema)

Question 11

How does increased sensitivity occur in asthma?

Answer 11

Epithelial damage leads to sensory nerve endings being exposed

Question 12

Test with what will reveal hyper responsiveness in asthma?

Answer 12

Inhaled bronchoconstrictors (spasmogens) e.g. histamine or metacholine

Question 13

Are asthma attacks immediate or delayed?

Answer 13

may be both

Question 14

How does allergic asthma develop?

Answer 14

• Antigen cross links IgE receptors
• Stimulates calcium entry into mast cells and release of calcium from intracellular stores
• This releases secretory granules containing histamine
• Other agents eg leukotrienes ,LTD4 and LTC4 are produced causing smooth airway muscle contraction
• Substances are released (e.g LTB4 and PAF and PGD2) to attract cells like mononuclear cells and eosinophils intro area

Question 15

In the late phase of asthma, what causes infiltration of cytokine release Th2 cells and monocytes and activation of inflammatory cells?

Answer 15

Chemotoxins and chemokines

Question 16

What do eosinophils and major basic cationic proteins cause?

Answer 16

epithelial damage and airway hyperreactivity

Question 17

In immediate asthma what causes bronchospasm?

Answer 17

Spasmogens caused by mast cells and mononuclear cells

Question 18

What kinases are involved in broncodilator action?

Answer 18

protein kinase A (PKA) and G protein receptor kinases (GRKs) – specifically B-adrenoceptor kinases

Question 19

What does B-arrestin act as in bronchodilator action?

Answer 19

a scaffold protein that links the desensitized B-adrenoceptors to ‘endocytic machinery’ that internalizes the receptor

Question 20

What does persistent activation of B2-adrenoceptors cause?

Answer 20

Receptor desentization and endocytosis (resulting in loss of function)

Question 21

Where does the action of B-arrestin occur?

Answer 21

clathrin-coated pits and vesicles

Question 22

What line of treatment are SABAs for asthma?

Answer 22

1st line

Question 23

What are useful for nocturnal asthma?

Answer 23

LABAs

Question 24

How are CystLT1 receptor antagonists used in asthma?

Answer 24

add on therapy in mild persistent asthma, especially exercise/antigen induced asthma, not for acute/severe cases

Question 25

Is isoprenaline a selective or non selective beta agonist?

Answer 25

non selective

Question 26

Are non selective beta agonists recommended in asthma?

Answer 26

No

Question 27

What is montekulast an example of?

Answer 27

CysLT1 receptor antagonists

Question 28

What are xanthines present in?

Answer 28

coffee, tea, chocolate-containing beverages