Asthma

Question 1

How do allergens trigger a type 1 hypersensitivity reaction in asthma?

Answer 1

Allergens from environment detected by dendritic cells

DCs present this to Th2 cells (in mucosal layer of bronchial wall)

This produces IL4 and IL5 cytokines

IgE Ab production - Type 1 hypersensitivity reaction

Question 2

What does IL4 cytokine do when activated?

Answer 2

produces IgE Abs → coat mast cells (in epithelial bronchial layer) and stimulate them to release granules which inflam mediators (eg histamines, leukotrienes, prostaglandins)

Question 3

What does IL5 cytokine do when activated?

Answer 3

activates eosinophils → enhances immune response, releases further cytokines and leukotrines (inflam mediator)

• leukotriene binds to leukotriene receptors on bronchial smooth muscle cells → constriction
• leukotriene binds to receptors on mucus glands (submucosa) → mucus secretion

Question 4

How do the chemical mediators released by lungs cause chronic lung damage?

Answer 4

after few hours: eosinophils release chemical mediators that damage lung endothelium

Over time these changes become irreversible oedema, scarring, fibrosis → thickening of epithelial basement membrane → reduced airway diameter

Question 5

Name some allergens and irritants which could trigger asthma

Answer 5

Allergens such as:
Pollen
Mold
Animal dander
Insect parts
Some chemicals

Irritants such as:
Smoke
Dust
Gas or Diesel fumes
Chlorine

Question 6

Difference between obstructive and restrictive lung disease?

Answer 6

obstructive: difficulty expiring air from lungs

restrictive: lung volume decreased, reduced intake of air

Question 7

Main difference between asthma and COPD physiology?

Answer 7

Asthma: airway narrowing due to muscle spasm - REVERSIBLE

COPD: airway narrowing due to chronic inflammatory damage to airways - IRREVERSIBLE

Question 8

Therapeutic effect of B2 agonist?

Answer 8

relax smooth muscle

Question 9

Therapeutic effect of muscarinic antagonist?

Answer 9

prevent smooth muscle contraction

Question 10

Difference between restrictive and obstructive lung disease?

Answer 10

Restrictive: lungs restricted from fully expanding, with less lung volume due to ↓ lung elasticity or caused by a problem related to the chest wall expansion

Obstructive: difficulty expelling air from lungs due to narrowing of the airways. too much air remains in lungs

Question 11

What effects does leukotriene have when activated y IL-5?

Answer 11

• leukotriene binds to leukotriene receptors on bronchial smooth muscle cells → constriction
• leukotriene binds to receptors on mucus glands (submucosa) → mucus secretion
• increases vascular permeability in airways
• attracts more immune cells to area

the overall effect of bronchoconstriction and inflammation causes airway obstruction

Question 12

What effect do prostaglandins have on smooth muscle cells?

Answer 12

similar to leukotrienes

they bind to receptors on SMCs (increase constriction) and mucus glands (inc mucus secretion)

increases vascular permeability in airways

attracts more immune cells to area

the overall effect of bronchoconstriction and inflammation causes airway obstruction

Question 13

Symptoms of asthma and copd

Answer 13

cough
wheeze
sob (dyspnea)
chest tightness