18 - Respiratory system

Question 1

1) How to measure airway obstruction?
2) If airway obstruction is permanent, it’s…
3) If reversible, likely…

Answer 1

1) Forced Expiration Volume (FEV)
2) COPD (not enough bronchodilators or corticosteroids)
3) Asthma

Question 2

Describe the difference between allergic and non-allergic asthma

Answer 2

Allergic:
- Atopic/extrinsic
- Common
- Systemic IgE -> inflamm
Non-allergic
- Non-atopic/intrinsic
- Uncommon
- Local IgE -> inflamm

Question 3

Describe the phases of allergic asthma

Answer 3

Immediate phase:
- Allergen + mast cell
- Mast cell makes spasmogens for bronchospasms
- Mast cell makes chemokines + chemotaxins
Late phase:
- Attracts Th2 and eosinophils in particular
- Makes EMBP, ECP = epithelial damage
- Airway hyperactivity -> bronchospasm, wheeze, cough…

Question 4

Tx of asthma? (2 total)

Answer 4

• Bronchodilators (reliever acts on bronchospasm in immediate phase)
• Inhaled corticosteroid (effective reliever and preventor which normalises lung function to prevent future need of bronchodilators)

Question 5

Describe inhaled glucocorticoids
- Mechanism?
- Time to improvement?
- Side effects?

Answer 5

• Downregulation of pro-inflammatory and upregulation for anti-inflammatory proteins
• > 6hr improvement
• Little to none systemically absorbed. Otherwise may have oral candidiasis and dysphonia (hoarse voice)

Question 6

Describe mast cell stabilisers in comparison to inhaled glucocorticoids

Answer 6

• Stabilises mast cell membrane, no histamine release
• Prophylactic use
• Doesn’t cause bronchodilation, less effective than inhaled corticosteroids
• Mostly for antigen- or exercised-induced asthma

Question 7

2 ways bronchodilators work?

Answer 7

Beta 2 adrenoceptor agonists:
- Direct acting smooth muscle dilator
- Also inhibits mediator release of mast cells
- Increases mucus clearance via cilia
- Either SABA (short-acting) or LABA (long-acting)
Phosphodiesterase inhibitors:
- Causes cAMP/cGMP increase = relaxation