What causes it & how can it be treated? View this slide deck to become familiar with cause and effect. Then look at the quiz below.

1. Airway narrowing in asthma:
What causes it & how can it be treated?
http://www.youtube.com/watch?v=7EDo9pUYvPE
http://www.youtube.com/watch?v=4aK76DoxKGk
http://www.youtube.com/watch?v=jmuWKSRqvKI
http://www.youtube.com/watch?v=JHLajTyxFPU
http://www.youtube.com/watch?NR=1&v=ycXgzPycCDM&fe
ature=endscreen
Perhaps, start with a general overview of asthma, as per these YouTube
clips, or other?

2. Airway narrowing in asthma: outcomes
At the completion of this module, students will understand that:
 airway narrowing is the primary cause of asthma symptoms
 mucous hypersecretion, airway wall thickening & broncho-
constriction are important determinants of airway narrowing
 airway narrowing also contributes to another characteristic
feature of asthma – airway hyperresponsiveness
 mast cell products are the key mediators of airway narrowing
in the “early phase reaction” of allergic asthma
 airway wall inflammation is an important driver of airway
narrowing in the “late phase reaction” of allergic asthma
 management of asthma typically involves effective use of both
controller and reliever medications

3. What is asthma?
1. An airways disease in which exposure to various provoking
stimuli (triggers) make airways narrow too much and too easily.
These triggers don’t cause narrowing in nonasthmatic people.
Airways don’t
narrow
Nonasthmatic
Airways
narrow
AsthmaticExposure to triggers
e.g.
 allergen
 respiratory virus
 exercise
 drugs, incl. aspirin
 irritants, smoke
 extreme emotions
etc. …

4. What is asthma?
2. In asthma, airway narrowing can cause bronchial obstruction
and airflow limitation, which leads to symptoms of
 wheezing
 breathlessness,
 chest tightness, and
 nighttime or early morning coughing.
These symptoms are variable, intermittent, worse at night
and provoked by triggers including exercise

5. AsthmaticNonasthmatic
What is asthma?
3. Airway narrowing ( internal diameter of airway) is
usually caused by variable combinations of:
 contraction of the airway smooth muscle that
surrounds the airways (bronchoconstriction)
 inflammation of the airways (e.g. thickened airway wall,
hypersecretion of mucous into the airway lumen).
Narrowed
airway
Normal
airway

6. The non-asthmatic airway
epithelium
basement
membrane
submucosal
glands
blood
vessels
lumen
goblet cell
smooth
muscle
cartilage
Illustration of cross-section of non-diseased bronchial tube –
airway lumen is clear and air will readily pass into and out of lungs

7. Pathologic features of asthmatic airways
reduced airway
lumen area
mucus gland
hypertrophy
goblet cell hyperplasia
smooth muscle
hyperplasia
subepithelial
fibrosis
increased
blood vessel
numbers
many inflammatory cells
Cross-section of asthmatic bronchial tube – airway lumen is
obstructed and air cannot easily pass into and out of lungs

8. Thus, airway narrowing in asthma is due to:
  mucus in lumen due to
stimulation of larger mucous
glands & more numerous
goblet cells
  thickness of airway wall
due to inflammation &
remodelling
  constriction of airway smooth
muscle by mediators released
in asthmatic airway
Asthmatic airway


