resp 2 lectures Flashcards
Trachea and bronchi have ciliated epithelial cells, goblet cells, submucosal glands
- number distribution throughout airways?
- functions?
- issue?
- Numerous in
trachea and bronchi; progressively fewer in distal airways - Function: clearance of mucus containing trapped particles
- Vulnerable to injury
Bronchioles: Club Cell
- what is it?
- function?
- non-ciliated cells in bronchiolar epithelium
- Function:
> Stem cell for regeneration
> Metabolism and detoxification
> Quell inflammatory responses
Causes of Airway Injury
- Some viruses injure both bronchiolar and alveolar epithelium (=bronchointerstitial pneumonia)
- Allergic or idiopathic inflammatory disease:
> Asthma in horses (aka heaves), cats
> Canine chronic bronchitis - Chronic irritants & oxidants:
> tobacco smoke, dust, inhaled chemicals, … - Toxic: Club cells metabolize chemicals, eg. 3-methylindole
Viruses that cause airway injury
& predispose to bacterial pneumonia
- cattle and sheep
- BHV-1
- BRSV
- PIV3
- Corona
Viruses that cause airway injury
& predispose to bacterial pneumonia
- swine
- Influenza
Viruses that cause airway injury
& predispose to bacterial pneumonia
- horse
- Influenza
- EHV-1
- EHV-4
Viruses that cause airway injury
& predispose to bacterial pneumonia
- dogs
- Distemper
- CPIV
- CAV-2
- Coronavirus
- Influenza
Viruses that cause airway injury
& predispose to bacterial pneumonia
- cats
- FHV-1
- Calici
Non-infectious inflammation of
small airways
- Asthma/heaves: cats, horses
- Canine chronic bronchitis
- Human asthma & COPD
Acute effects of airway disease
- Failure of mucociliary clearance > bacterial pneumonia
- Airway obstruction due to:
> smooth muscle contraction (bronchoconstriction), triggered by inflammatory mediators such as leukotrienes, other eicosanoids, or cytokines
> inflammation and edema of the airway wall
> exudates and necrotic cells within the lumen
Airway Injury: Effects on Lung Function
- decreased alveolar ventilation > hypoxemia hypercapnea
- increased expiratory effort & work of breathing
> airways collapse, air gets trapped in lung
Airway Injury: Bronchitis, Bronchiolitis and Bronchiolar Necrosis
- sequelae
– Repair
– Bronchiolitis fibrosa obliterans
– Chronic bronchiolitis: metaplasia, neoplasia
Repair of Bronchiolar Injury
What if healing is delayed by extensive damage, or ongoing necrosis?
- Club cells proliferate & repopulate airway epithelium
- Differentiation into ciliated cells
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Healing delayed: fibrosis, which can permanently affect the function of the lung
Bronchiolitis fibrosa obliterans
Obliterative bronchiolitis
- what is this?
- Erosion of epithelium
- Exudation of fibrin and leukocytes into lumen
- Infiltration of fibroblasts
- “Organization” by fibrosis
Sequelae to Chronic Irritation, Inflammation, or Necrosis of the Airways
Ciliated epithelium is sensitive to injury
* Mucous metaplasia: protective adaptation
* Squamous metaplasia: protective adaptation
* Neoplastic transformation
Airway Injury:
Bronchitis, Bronchiolitis and Bronchiolar Necrosis
- cause
- acute effects
- sequelae
Causes:
* Viruses
* Chronic irritants
* Allergic
* Toxic
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Acute effects:
* Failure of mucociliary clearance
* Obstruction to airflow by exudate, edema, and bronchoconstriction
* Failure of alveolar ventilation…
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Sequelae:
* Repair
* Bronchiolitis obliterans
* Mucous or squamous metaplasia
* Neoplastic transformation