Respiratory Block PATHOLOGY L1. Pathology of bronchial asthma Dr. Maha Arafah. 2013, Feb. Objectives. At the end of this lecture, the student should be capable of:
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Pathology of bronchial asthma
Chronic Obstructive Pulmonary Disease
Until recently, airway remodeling was considered a late, secondary change of asthma
the current view suggests that it may occur over several years before initiation of symptoms.
1. Chronic airway inflammation.
2. Bronchial hyperresponsiveness.
1. acute response (within minutes)
2. a late phase reaction (after 4-8 hours)
Late phase reaction
Recruitment of leukocytes mediated by product of mast cells:
1. Eosinophiland neutophilchemotactic factors
2. IL-4 & IL-5 and induceTH2 subset ofCD4+ T cells
3. Platelet-activating factor
4. Tumor necrosis factor.
Late phase reaction:
1. Release of more mediators to activate more mast cells
2. Cause epithelial cell damage
Eosinophils produce major basic protein, eosinophilic cationic protein and eosinophilperoxidase ( toxic to epithelial cells).
1. IgE production by B cell (IL4)
2. Growth of mast cells (IgE)
3. Growth and activation of eosinophils (IL5)
4. mucous secretion (IL13)
1. Drug-induced asthma (Aspirin or nonsteroidal drug sensitivity)
2. Occupational asthma ( fumes, dusts, gases)
(1) Episodic expiratory wheezing (inspiratory as well when severe)
(2) Nocturnal cough
(3) Increased anteroposterior diameter
In fatal cases, grossly, the lungs are overdistended because of overinflation, and there may be small areas of atelectasis.
The most striking macroscopic finding is occlusion of bronchi and bronchioles by thick, tenacious mucus plugs.
(1) Initially develop respiratory alkalosis
(a) Patients work hard at expelling air through inflamed airways.
(b) May progress into respiratory acidosis if bronchospasm is not relieved
Normal pH or respiratory acidosis is an indication for intubation and mechanical ventilation.
(2) Eosinophilia, positive skin tests for allergens
1] Definitions of asthma as one of the chronic obstruction airway diseases.
2] Types and pathogenesis of extrinsic (immune) asthma and extrinsic (non-immune) asthma.
3] Clinical presentation and pathological changes seen in the bronchial tree in cases of asthma.
4] Complications of asthma: superimposed infection, chronic bronchitis and pulmonary emphysema.
5] Definition and manifestations of status asthmaticus.