EX. 3 - Asthma Flashcards
Episodic bronchospasm resulting form an exaggerated bronchoconstrictor response to various stimuli
Asthma
Asthma is an - of the bronchi
Inflammation
Episodic bronchospasm causes
Dyspnea, cough, and wheezing
Asthma affects -% of adults and -% of children
5% adults
7-10% children
(Over 3,000 fatalities a year)
Types of asthma
Extrinsic (allergic/classical)
Intrinsic
Extrinsic asthma:
Hypersensitivity rxn induced by exposure to an extrinsic antigen (dust, mold, pollen)
Commonly associated w/other allergy in patient/family members
Onset - early in life
Elevated serum IgE levels and eosinophil count
Driven by TH2 subset of CD4+T cells
Intrinsic asthma
Nonimmune triggering mechanism (ex. aspirin, viral infection, cold, psychological stress, exercise)
No personal or family history of allergy
Serum IgE levels - normal
Two phases of extrinsic asthma attacks
Acute bronchoconstriction
(immediate; 30-60 min)
Sustained bronchoconstriction:
(Late; 4-8 hours later after immediate response)
Acute bronchoconstriction
Immediate asthmatic response (IAR)
Occurs after sensitization
Mediated by IgE, produced in response to exposure of foreign particles
(IgE binds to FcER-1 on mast cells in the airway mucosa
Re-exposure to the allergen triggers the release of mediators from the mast cells in a process called
mast cell degranulation
Mast cells release
Histamine
Tryptase
Leukotrienes (LTC4 and LTD4)
Prostaglandin D2 (PGD2)
Mediators of acute bronchoconstriction cause
Smooth muscle contraction and vascular leakage
Sustained Bronchoconstriction
Late asthmatic response (LAR)
(3-6hrs after acute)
Caused by Activation of TH2 cells and cytokine production
Activation of TH2 cells in sustained bronchoconstriction
Ex. IL5, IL9, IL13
Attract and activate eosinophils
Stimulate mucus hypersecretion by bronchial epithelial cells
Stimulate IgE production by B lymphocytes
Activation of eosinophils
Release major basic protein, (MBP), eosinophil cationic protein (ECP) peroxidase, - causes tissue damage
Epithelium remodeling
Hyperplasia
Hypersecretion
Basement membrane remodeling
Thickening
Smooth muscle remodeling
Hypertrophy