resp 1 lectures Flashcards
club cells
- location and function
- in smaller airways
- progenitor cells to replace damaged ciliated epithelium
> metabolize and detoxify chemicals and drugs in some species
> secrete proteins that help to regulate the inflammatory response
- Nasal cavity and nasopharynx functions
– Air conduction
– Removal of large particulates
– Warming and humidification of air
– Olfaction
Trachea, bronchi, bronchioles functions
– Air conduction
– Defence
Alveoli function
gas exchange
Cells in the Respiratory Tract: Trachea & bronchi
- Ciliated epithelial cells
- Goblet cells & mucosal glands
Cells in the Respiratory Tract: Bronchioles
- Few ciliated epithelial cells or goblet cells,
no mucosal glands - Club cells: non-ciliated cells
Cells in the Respiratory Tract: Alveoli
*Type I pneumocytes (membranous)
*Type II pneumocytes (cuboidal) > progenitors, surfactant
*Alveolar macrophages
Pulmonary Intravascular Macrophages
- in vessels of what animals? not normally in?
- functions?
*Macrophages in blood vessels of:
cat, horse, ruminants, pig
*But not normally in:
dog, rodents, humans
*Removal of particulates from blood (bacteria, opsonized RBCs, …)
Anatomic Patterns of Pneumonia
- Bronchopneumonia
- Airway disease
- Interstitial lung disease (aka interstitial pneumonia)
- Embolic pneumonia
Bronchopneumonia
- cause
- gross lesions
- hitso lesions
- Cause: airborne bacterial infection, with infection of airspaces
- Gross lesions: usually cranioventral consolidation
- Histologic lesions:
> Neutrophils & edema fill alveoli and bronchioles
> Often no damage to airway or alveolar epithelium
Airway disease
- what is it?
- cause
- common examples
- Inflammation and/or necrosis of bronchi and/or bronchioles
- Cause: viruses, bacteria, hypersensitivity
- Examples
> Influenza virus: bronchial and bronchiolar necrosis
> Chronic bacterial bronchitis
> Chronic bronchitis in dogs
> Equine, feline, human asthma
Interstitial lung disease “Interstitial pneumonia”
- what is the interstitium?
- what is it?
- cause
- gross lesions
- histo lesions
- repair?
- Interstitium = alveolar septa and other connective tissue
<><><><> - Injury to alveolar epithelium or endothelium
- Cause: viruses, sepsis, toxins, hypersensitivity, idiopathic
- Gross lesions: diffusely rubbery
- Histologic lesions:
> Hyaline membranes
> Repair: proliferation of type II pneumocytes, interstitial fibrosis
Embolic Pneumonia
- what is this?
- lesions?
- Blood-borne showering of the lungs by bacterial or fungal pathogens, (ddx= metastatic neoplasia)
- Lesions: generalized, randomly distributed foci of suppuration ± necrosis, centred on blood vessels
Horse, embolic pneumonia with aspergillus, pethogenesis?
Colitis > loss of mucosal barrier > hematogenous spread of Aspergillus
Anatomic Patterns of Pneumonia, summary with brief cause
- Bronchopneumonia: Inflammatory exudates fill the air spaces
- Airway disease: Inflammation or injury to bronchi / bronchioles
- Interstitial lung disease (interstitial pneumonia): Injury to alveolar epithelium (or endothelium)
- Embolic pneumonia: Blood-borne insult
The Need for Lung Defences
- Most bacterial respiratory pathogens are carried by apparently healthy animals
- The lungs are constantly challenged with pathogens from the nasopharynx and in inhaled particles
- The lung must remain sterile for optimal function
how fast do lungs cleat pathogens, eg. M. haemolytica?
only ~25% of pathogen after 2 hours, ~10% at 4…
Multi-layered System of Lung Defence
- Mucociliary clearance
- Proteins in lung lining fluid
- Resident Alveolar Macrophages
- Recruited cells…
what is mucociliary clearance?
- purpose, mechanism
Mucociliary clearance & cough rapidly eliminates inhaled particles
* Periciliary layer (hypophase) and mucous layer
* Trapping of particles by mucus
* Clearance of mucus to the nasopharynx
Proteins in lung lining fluid
- what do they do?
- which ones?
Proteins in lung lining fluid block colonization, kill or opsonize bacteria that reach the lung
* Antibody
* Surfactant proteins A & D
* Defensins
* Lactoferrin
* Lactoperoxidase
Resident Alveolar Macrophages - functions
- Phagocytosis of particles & bacteria
- Killing pathogens
- Recruitment of inflammatory cells
- “Housekeeping” in the alveoli
Recruited cells for lung defence
- which ones, and what do they do?
…enhance lung defences
* Neutrophils, monocyte- derived macrophages: phagocytose & kill bacteria
* B lymphocytes: antibody blocks colonization, kills bacteria, opsonization
* T lymphocytes: activate macrophages-> increased microbicidal functions
Summary of Lung Defences
- Particle entrapment
- Mucociliary clearance & cough
- Proteins in lung lining fluid
- Alveolar macrophages
- Recruitment of neutrophils & monocyte-derived macrophages
- Immune responses: neutralize pathogens, block colonization, enhance cell function
shipping fever - usually presents as what type of pneumonia
Fibrinopurulent bronchopneumonia
Pneumonia and pleuritis =
- how does it develop?
Pleuropneumonia
- Most cases have an underlying bronchopneumonia, with pleuritis developing as bacteria migrate into the pleural space
Earliest lesions of bronchopneumonia: 3 hours post-infection.
neutrophils in distal bronchioles, no clinical signs yet
Sequelae of Bovine Bacterial Pneumonia
- Acute: death due to sepsis
<><> - Chronic bronchopneumonia
- Pleural adhesions, lung fibrosis
<><> - Abscessation
- Sequestrum formation
- Bronchiectasis
Bronchiectasis - what is this?
Pooling of exudates > Neutrophil-mediated degradation of bronchial wall
Sequestrum formation… what is a sequestrum?
mass of necrotic tissue surrounded by fluid exudate… cannot be removed & persists
Abscess, Bronchiectasis, Sequestrum: Clinical Importance?? Clinical Outcome??
- Permanent
- Inaccessible to many antibiotics
- Refuge for pathogens > relapse
Summary: Bronchopneumonia progression
- Multilayered system of lung defences
- Compromised lung defence > air-borne infection by opportunistic pathogens
- Cranioventral consolidation;
Histologic lesions: bronchioles and alveoli filled with neutrophils ± fibrin - Resolution;
Chronic bronchopneumonia,
abscessation, bronchiectasis, sequestration
Feedlot calf, liver abscess erodes into hepatic vein and caudal vena cava
> Acute showering of lung with myriad bacteria
- what is the pattern of lung disease?
c) Interstitial lung disease
