Respiratory System Flashcards
What is the division between the upper and lower respiratory tracts?
thoracic cavity —> cranial to thoracic inlet = URT
What makes up the conducting system? What does it do?
nasal cavity, paranasal sinuses, larynx, trachea, and bronchi lined by pseudostratified columnar ciliated epithelium and goblet cells
nasal conchae and turbinates increase surface area to increase the humidity and temperature of inhaled air
What makes up the transitional system?
bronchioles lined by non-ciliated secretory cells, club (Clara) cells, important for the detoxification of xenobiotics
club cells contain CYP450
What do healthy bronchioles lack?
goblet cells
What makes up the exchange system?
alveolar ducts and alveoli enveloped by rich network of pulmonary capillaries and lined by epithelial type I (membranous) and type II (granular) pneumocytes
I = thin single squamous, O2 and CO2 exchange
II = thick cuboidal, secretes surfactant and replaces type I upon injury
What is the dual blood supply of the lungs?
- pulmonary arteries that conduct deoxygenated blood from the right side of the heart
- bronchial arteries that carry oxygenated blood
What are some other functions of the respiratory system other than gas exchange?
- phonation
- olfaction
- temperature regulation
- acid-base balance
- pressure regulation
all functions can be affected by respiratory disease
How does the oral and respiratory epithelium compare?
ORAL = pseudostratified columnar
RESPIRATORY = columnar ciliated
What does the mucociliary escalator do?
traps foreign pathogens in mucous and uses cilia to move them out of the respiratory system
Where is the normal flora found in the respiratory system?
most proximal region of the conductive system: nasal cavity, nasopharynx, larynx, and tracheal
- distal portions are considered sterile
What are the 2 types of defense mechanisms that keep the distal portion of the respiratory system sterile?
- NON-SPECIFIC (non-immune-mediated): mucous trapping, mucociliary clearance, phagocytosis, air turbulence generated by coughing and sneezing
- SPECIFIC (immune-mediated): antibody production, antibody-mediated phagocytosis, cell-mediated immunity
What macrophages are found in all species’ respiratory systems? What 2 are species-specific?
alveolar macrophages (PAMs) - engulf pathogens and are moved out by the mucociliary aparatus
- intravascular macrophages (PIMs) - present in ruminants, cats, pigs, and horses, and attach to alveolar capillaries and filter out pneumotoxins/pathogens in the blood
- Kupfer cells/splenic macrophages - present in dogs, humans, and lab rodents and remove bacteria and other particles from blood
How do alveolar macrophages (PAMs) protect from pathogens?
use pseudopodia to move and engulf pathogens, then form a phagolysosome to degrade it with proteolytic enzymes
What factors predispose animals to bacterial pneumonia?
- viral infections
- stress (BRDC)
- dehydration
- pulmonary edema
- uremia
- ammonia (poorly ventilated farms)
- immunosuppression/deficiency
Normal lungs, pig:
How is the nasal cavity viewed upon necropsy? How should it look?
sagittal section of the head
pink mucous membrane covering turbinates, lacking exudate
- normal gray discoloration of lymphoid tissue
What is a common cause of unilateral epistaxis in older horses? How is it typically diagnosed?
ethmoidal hematoma found in the back of the nasal cavity near nasal turbinates - pedunculated tumor-like lesion
endoscopy
Ethmoidal hematoma:
common in older horses and causes unilateral epistaxis
How does infectious bovine rhinotracheitis affect the nasal cavity?
causes fibrinous rhinitis, forming a diphtheritic membrane
Infectious bovine rhinotracheitis:
not as severe - mucosuppurative exudate, congested and hemorrhagic mucous membrane
What species of bot commonly infects sheep nasal cavity? What does it cause?
Oestrus ovis - nasal bot
rhinitis —> fly deposits egg in nares and irritates; upon hatching, bots can reach the sinus
What is a rare sequel of Oestrus ovis infection?
aberrant migration of larvae —> penetrates cribriform plate and reaches the brain, causing meningoencephalitis
What is thought to cause atrophic rhinitis? What are some common signs?
combined infection of Bordetella bronchiseptica and Pasteurella multocida types D and A
- upper respiratory disease
- nasal discharge
- lateral deviation of snout/nasal septum near the first and second premolars
Atrophic rhinitis, pig:
- lateral deviation of nasal septum
- atrophied turbinates
- more suscpetible to respiratory disease, leading to pneumonia (turbinates usually warm and humidify air)
How does infection cause atrophic rhinitis? Where is affected most?
toxigenic strains of Pasteurella multocida produce cytotoxins that inhibit osteoblastic activity and promote osteoclastic reabsorption of the nasal turbinates
ventral scroll of the ventral nasal tubrinate
What causes inclusion body rhinitis? What animals are most affected?
porcine cytomegalovirus and herpesvirus 2 (SHV-2)
usually pigs 3-5 weeks, but can cause fatal systemic infection in younger suckling pigs under 3 weeks
- increased cell size and nuclei with large basophilic inclusions
How does feline herpesvirus 1 typically affect the respiratory system?
rhinitis and conjunctivitis —> usually transient, but kittens in poor body condition can develop severe disease
How does feline calicivirus typically affect the respiratory system?
oculonasal discharge with vesicular and ulcerative stomatitis and interstitial pneumonia
Feline calicivirus:
How can ulcerative stomatitis from feline calicivirus infection be differentiated from uremic glossitis?
NOT ventral or marginal —> results from burst vesicles
Feline calicivirus, pneumonia:
diffuse, INTERSTITIAL
What is the cause of granulomatous rhinitis in dogs? When is it common for dogs to become infected?
Rhinosporidum seeberi, a rare aquatic protistan parasite
dogs in the Midwest and Southern US that have been in contact with stagnant water
Granulomatous rhinitis, dog:
- Rhinosporidum seeberi
- proliferative, tumor-like
What typically causes guttural pouch tympany in foals?
congenital problem with Eustachian tube causing entrapment of air within the guttural pouch
- typically no pain upon touch, seems inflammed
What causes Strangles in horses? What does this cause?
Streptococcus equi
lymph node and guttural pouch involvement, resulting in suppurative accumulation within the guttural pouch and eustachitis
+ fistulous tracts