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What are the 2 major components of the mucociliary elevator?
mucus sheet (goblet cells, serous cells), ciliated epithelium (cilia beat in serous layer, move mucus upward toward nose/pharynx)
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What are the components of pulmonary clearance (getting rid of what got in, that shouldn't be there)? (2)
mucociliary elevator, pulmonary alveolar macrophages
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What are the main functions of the pulmonary alveolar macrophages (PAMs)? (3)
phagocytize particulares that reach alveoli, move them out of the lungs, and/or transport particles to lymph nodes to elicit immune response
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Describe the concept of anatomic geometry.
the respiratory system is a series of tubes with progressively decreasing diameter from the nasopharynx; therefore, the surface area to volume ratio in the large tubes (trachea) is low, but it is high in small tubes (bronchioles)
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Diseases dependent on surface area, such as _____________, are most important where surface area is __________ with respect to volume.
inflammation; large
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Diseases which impinge on volume, such as ___________, are most important where volume is __________ compared to surface area.
obstruction; small
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What are the functions of the nasopharynx? (4)
conduction of air, filtration of air, clearance of particulates, air modification
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What developmental abnormalities lead to diseases obstructing airflow in the nasopharynx? (3)
- brachycephaly (reduced luminal space)
- stenotic nares (alar fold abnormalities)
- choanal atresia (camelids)
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What categories of disease can cause obstruction of airflow in the nasopharynx? (3)
developmental abnormalities, inflammation, space-occupying masses
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Inflammatory causes of obstructed airflow in the nasopharynx. (5)
viral, bacterial (usually secondary to viral), fungal (aspergillus, cryptococcus), immune mediated, parasitic (rare)
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What types of space-occupying masses can cause obstruction of airflow in the nasopharynx? (3)
neoplasms, inflammatory polyps, granulomas/abscesses (Aspergillus, Rhinosporidium)
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What are the 3 most common neoplasms that obstruct airflow in the nasopharynx?
nasal adenocarcinoma (dogs), lymphoma (cats), squamous cell carcinoma (horses) [almost always malignant]
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What are inflammatory polyps?
non-neoplastic proliferative masses composed of stroma, epithelium, and inflammation (most common in cats)
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What are some diseases leading to loss of filtration and air modification? (2)
palatoschisis (cleft palate), progressive atrophic rhinitis of swine
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How does palatoschisis lead to loss of filtration and air modification?
ingest passes from oral cavity to nasal cavity, causing rhinitis +/- aspiration pneumonia
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What are the etiologic agents of progressive atrophic rhinitis of swine?
Pasteurella multocida type D +/- Bordatella bronchiseptica
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Dermonectrotic toxin associated with progressive atrophic rhinitis in pigs leads to...
reduced osteoblast bone formation and increase osteoclast bone resorption--> turbinate atrophy and distortion of the snout--> bacterial bronchopneumonia
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Destruction of the filtration and air modification structures (turbinates) predisposes to...
lower respiratory tract disease (pneumonia).
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What are the functions of the larynx? (3)
air conduction, air filtration/particulate clearance, protection of lower respiratory tract during deglutition
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Describe the anatomic geometry of the larynx and potential consequences of obstruction.
narrow lumen, small SA, no auxiliary air flow--> easily obstructed with catastrophic consequences
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Major causes of obstruction of air flow in the larynx. (5)
developmental- elongated soft palate, epiglottal entrapment in brachycephalics, laryngeal hemiplagia (roarers), laryngeal paralysis in dogs, inflammation (laryngitis), neoplasia (uncommon)
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What is the fundamental cause of roarers?
degeneration of left recurrent laryngeal nerve, resulting in left cricoarytenoid muscle atrophy--> failure to abduct arytenoid--> inspiratory stridor
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What are causes of laryngeal paralysis in dogs?
idiopathic, polyneuopathy, hypothyroidism
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What are etiologies o laryngitis in cattle? (3)
BHV-1, Fusobacterium necrophorum, trauma (baling gun injury)
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What neoplasias are most common for obstructing the larynx? (2)
lymphoma (cats), squamous cell carcinoma (dogs)
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What causes calf diphtheria?
calves weaned--> bawling constantly--> vocal folds smack together, causing trauma--> infection with local flora--> fibronecrotic exudate obstructs lumen of larynx
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What are the functions of the trachea and bronchi? (2)
air conduction and filtration, particulate clearance through mucociliary elevator
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____________ of the trachea and bronchi are usually unimportant in large animals due to the large diameter, but these same diseases can be life-threatening in smaller animals.
Inflammation
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What types of diseases of the trachea and bronchi cause obstruction of air flow? (4)
developmental, degenerative, inflammation, neoplasms
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What types of developmental diseases of the trachea and bronchi cause obstruction of air flow? (1)
tracheal hypoplasia in brachycephalic dogs
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What types of degenerative diseases of the trachea and bronchi cause obstruction of air flow? (1)
tracheal collapse- middle aged miniature dogs due to dorsoventral narrowing
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What examples of inflammatory diseases of the trachea and bronchi cause obstruction of air flow? (4)
- viral- herpes viruses, paramyxovirus, adenovirus
- bacterial- Bordatella bronchiseptica
- parasites- Dictyocaulus viviparous, Syngamus, Oslerus
- immune-mediated- feline asthma, heaves in horses
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What is an example of a neoplasm of the trachea and bronchi cause obstruction of air flow? (1)
granular cell tumors in horses
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Permanent dilation of bronchi as a result of chronic bronchial obstruction and infection.
bronchiectasis
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What are the major events of bronchiectasis and how do they lead to chronic infections? (8)
- 1- severe and chronic inflammation
- 2- destruction of bronchial walls
- 3- obstruction of lumen by inflammatory exudate
- 4- weakening of bronchial wall
- 5- scar tissue (fibrosis) formation
- 6- reduced filtration efficiency
- 7- net accumulation of particles
- 8- chronic infections
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Defect in ciliary function so that they cannot move the mucus sheet; can also manifest with situs inversus and infertility (sperm cannot move).
Ciliary dyskinesis
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Reduced temperature, dehydration, reducing clearance of pathogens by causing ____________.
physical impairment of cilia
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What viral and bacterial agents cause decreased ciliary clearance? (1 of each)
IBR in cows, Bordatella
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What types of diseases can result in reduced clearance of pathogens? (5)
ciliary dyskinesis, physical impairment, chemical irritation, infectious agents, inflammation
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____________ is a major effect of disease of the trachea and bronchi.
Reduced particle clearance
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Functions of the bronchioles. (2)
air conduction, clearance
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What accounts for the increased deposition of particles within the bronchioles, and what is the consequence of this?
rapid reduction in air velocity at the bronchioles--> many aerogenous insults affect this region
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Describe the sequence of events that leads to obstruction of the bronchioles. (5)
- 1- exudate accumulation due to inflammation +/- epithelial damage
- 2- narrowing of airway lumen, inhibiting airflow
- 3- rapid spread to alveoli--> pneumonia
- 4- chronic inflammation
- 5- proliferation, mucus secretion, and obstruction
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What epitheliotropic viruses target the bronchioles? (4)
CDV, BRSV, herpesviruses, influenza
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Partial or complete collapse of the lung.
atelectasis
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___________ tend to be the primary site of particle accumulation, leading them to be the first affected in aerogenous disease (bacterial pneumonia).
Bronchioles
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Infection/inflammation of bronchioles often spread to ___________, causing __________.
alveoli; pneumonia
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What is the function of alveoli?
gas exchange
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Total alveolar surface area is _______; therefore, ________ disease is less important than _________ disease.
large; focal; diffuse
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Processes that _____________ reduce gas exchange in the lungs.
increase the thickness of the alveolar gas exchange barrier
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What are some disease processes that increase the thickness of the alveolar diffuse barrier? (4)
edema, exudate, cellular proliferation, cellular metaplasia
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Inflammation centered on bronchioles with secondary spread to alveoli.
bronchopneumonia
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Bronchopneumonia frequently has an ___________ portal of entry.
aerogenous
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What is the usual distribution of bronchopneumonia?
cranioventral distribution
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At what percent of lung affected does bronchopneumonia generally become life-threatening?
30%
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What are bacterial causes of bronchopneumonia in ruminants? (5)
Manheimia haemolytica, Histophilus somni, Pasteurella multocida, Truperella pyogenes, Mycoplasma
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What are bacterial causes of bronchopneumonia in horses? (3)
Streptococcus spp., Rhodococcus spp., Actinobacillus equuli
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What are bacterial causes of bronchopneumonia in swine? (5)
Streptococcus suis, Haemophilus parasuis, Mycoplasma, Bordatella bronchisepticus, Actinobacillus suis
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What are bacterial causes of bronchopneumonia in dogs and cats? (3)
Streptococcus spp, E. coli, Pasteurella multocida
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Inflammation centeres on the air-blood barrier.
interstitial pneumonia
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Interstitial pneumonia frequently has a(n) __________ portal of entry or is part of a __________.
vascular; disseminated disease (viral pneumonia)
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What is the usual distribution of interstitial pneumonia?
diffuse distribution
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What are causes of interstitial pneumonia? (6)
bacterial septicemia, viremia or viral pneumonia, protozoa (Toxoplasma gondii in kittens), toxins, immune-mediated, acute respiratory distress syndrome
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What is a critical sequelae to pneumonia?
systemic hypoxia
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What are the 2 possible end points of pneumonia?
- tissue recovery--> restoration of pulmonary structures
- tissue loss and replacement--> chronic fibrosis--> reduced gas exchange
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Collapse of alveoli or failure of the alveoli to inflate, reducing ventilation.
atelectasis
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What are examples of diseases that cause atelectasis? (4)
pleural fluid, pneumothorax, space-occuying masses, exudate in airways
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Abnormal, permanent enlargement of air spaces accompanied by destruction of alveolar walls.
emphysema
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Emphysema causes __________ lung compliance, leading to decreased _____________ and inability to ___________.
increased; elasticity; expel air
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What is the most common form of emphysema in domestic species?
interstitial emphysema (air in interlobular septae)
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Fluid accumulation in the interstitium or alveoli.
pulmonary edema
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Pulmonary edema leads to increased __________, which can result in __(3)__.
capillary hydrostatic pressure; left-sided heart failure, hypotensive shock, capillary damage
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Pulmonary edema can cause an obstruction of ___________ in the lung or mediastinum.
lymphatics
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Physically, pulmonary hemorrhage has the same effect as ________.
edema
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Occlusion of pulmonary arteries by intraluminal mass.
pulmonary embolism
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What are potential causes of pulmonary embolism? (3)
Dirofilaria immitus adult worms, metastatic neoplasia, protein-losing disease
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What is infarction of the lungs rare in animals?
dual blood supply- pulmonary and bronchial
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What types of space-occupying masses occur in the lungs? (3)
neoplasms, abscesses, granulomas
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What is the function of the pleural cavity?
supports mechanics of ventilation--> expansion volume, negative pressure
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What are the types of pleural effusion and a cause of each? (3)
- hydrothorax- congestive heart failure
- chylothorax- ruptured thoracic duct, neoplasia
- hemothorax- trauma, rodenticide toxicity, hemangiosarcoma
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Pleuritic inflammation.
pyothorax
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What space occupying masses can affect the pleural cavity? (3)
neoplasms, abscesses, visceral masses causing diaphragmatic hernia
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Describe acute pleuritis versus chronic pleuritis.
- acute: painful, voluntary restriction of ventilation
- chronic: fibrous adhesions restrict respiration
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