Unit 3 - Respiratory Lecture 1 Flashcards
What are the components of the upper respiratory tract?
nasal cavity, sinuses, nasopharynx, larynx, and trachea
What is the mucosa of the upper respiratory tract composed of?
ciliated, pseudostratified columnar epithelium, goblet cells, and submucosal glands
What is the function of the mucosa in the respiratory tract?
generates, maintains, and moves mucus bilayer of the mucociliary apparatus
What are the primary functions for the upper respiratory tract?
warm and humidify air, cleanse air, initial defense against pathogens, conduct air to lower respiratory tract
How does the upper respiratory tract condition/clean air?
warm and humidify air, remove particulates, antigen sampling
What is the ‘design’ of the upper respiratory tract and what does it allow for?
large surface area for increased contact, moist surface for humidification, highly vascularized for heat exchange, cause turbulence for mixing of air, extensive network of dendritic cells for capturing invading organisms
What allows the upper respiratory tract to move air efficiently?
the smooth, straight, large diameter tube that is the trachea (and bronchi)
What happen when a foreign particle enters the respiratory tract?
Turbulence shoots it into the mucus bilayer where it is remobed by coughing, sneezing, or the mucociliary bilayer
What are the components of the mucociliary escalator?
surface mucus (the lower liquid layer and the more viscous gel layer) and cilia
How does the mucociliary escalator work?
mucus coats the surface, inspired particles become trapped in the mucus, cilia sweeps mucus towards the throat, mucus is swallowed, many infectious agents are destroyed in the stomach
What is primary ciliary dyskinesia?
when the cilia are not functioning properly in the mucociliary escalator
When do clinical signs associated with primary ciliary dyskinesia become apparent?
2-12 weeks of age
What clinical signs are associated with primary ciliary dyskinesia?
nasal discharge and a rattling, raspy or snorkeling sound when the animal breathes
What complications are associated with primary ciliary dyskinesia?
fluids/mucus and pathogens are not effectlively cleared making affected animals very susceptible to bacterial infections
How can primary ciliary dyskinesia be misdiagnosed as?
bronchitis, bronchiectasis, and bronchopneumonia
What is the role of the microflora in the respiratory tract?
it competes for attachment sites, stimulates immunity, and induces production of innate defense factors
What are the bronchi and bronchioles made up of?
ciliated, columnar epithelium, with goblet cells, +/- submucosal glands
What are the terminal and respiratory bronchioles made up of?
simple non-ciliated cuboidal epithelium - no glands
What is the alveoli made up of?
simple flattened epithelium, cuboidal epithelium, and alveolar macrophages
What do the cuboidal epithelium of the alveoli produce?
surfactant
What is the function of the alveoli?
gas exchand and acid base balance
What occurs to the cilia in the cold and therefore to mucus?
the cilia become sluggish or stop and mucus thickens
What does heat, low humidity, and dehydration do to mucus?
it dries it out resulting in decreased mucus clearance
What can lead to a decreased immune response in the respiratory tract?
immunodeficiency disorders and viruses
What can cause airway epithelial damage?
air pollutants, chemicals, viruses, and bacteria
What is the most costly disease of beef cattle?
bovine shipping fever
What causes bovine shipping fever (disease not agent)?
a bacterial pneumonia
The bacteria in the respiratory tract are typically opportunists. What allows them to cause shipping fever?
environmental and management factors that interfere with the respiratory defenses allowing the resident bacteria to cause disease
What are considered the ‘ultimate’ causes of bovine shipping fever?
stress, dust/ammonia, viruses
How does stress lead to bovine shipping fever?
stress leads to increased corticosteroid levels and thus immunosuppresion
How does dust/ammonia lead to bovine shipping fever?
it decreasses mucociliary clearance
How do IBR, PI3, and BRSV lead to bovine shipping fever?
they decrease mucociliary clearance and alter innate immunity (decrease TLR expression and defensins)
How does BVDV lead to bovine shipping fever?
it supresses alveolar macrophage function and causes a sustained neutropenia
What does CIRD stand for?
Canine Infectious Respiratory Disease
What does BRDC stand for?
Bovine Respiratory Disease Complex
What does PRDC stand for?
Porcine Respiratory Disease complex
Environmental factors + upper respiratory virus = ?
predisposition to bacterial bronchopneumonia
How does the upper respiratory tract respond to mild acute injury due to an inhaled agent?
acute inflammation: hyperemia and serous exudate (contains IgM and IgG)
How does the upper respiratory tract respond to severe acute injury?
acute inflammation with epithelial necrosis: ulceration and adherent fibrinonecrotic membrane
What two things result from chronic injury to the upper respiratory tract?
chronic inflammation and squamous metaplasia
What is chronic inflammation characterized as in the upper respiratory tract?
goblet cell and mucous gland hyperplasia which produces a thick, mucoid exudate
What is squamous metaplasia characterized as in the upper respiratory tract?
loss of mucocilliary apparatus (no cilia), mucosal drying (no goblet cells), and microflora changes
What are some expected clinical signs of infectious upper respiratory tract disease?
nasal discharge and sneezing, runny eyes (conjunctivitis), and cough and fever
What are some potential consequences of infectious upper respiratory tract disease?
a negative impact on the mucociliary apparatus, diminished conditioning of the air, decreased mucosal defense mechanisms, and increased access to lungs by particulate material
What does IBR stand for?
infectious bovine rhinotracheitis
What are the common herpesviral infections in cattle, horses, cats, and pigs?
IBR, equine rhinopneumonitis, feline viral rhinotracheitis, pseudorabies (PRV - swine)
What classic lesions does equine rhinopneumonitis cause?
mild, necrotizing rhinitis, tracheitis, and bronchiolitis
What is equine rhinopneumonitis caused by?
EHV-1 and EHV-4
What classic lesions does feline viral rhinotracheitis cause?
mucopurulent and ulcerative rhinitis and tracheitis
What can lower respiratory tract injury cause in the airways?
bronchitis/bronchiolitis, bronchiectasis, and bronchiolitis obliterans
What can lower respiratory tract injury cause in the alveoli?
atelectasis, edema, bronchopneumonia, and emphysema
What can lower respiratory tract injury cause in the interstitium?
interstitial pneumonia
What is the pathogenesis of necrotizing bronchitis/bronchiolitis?
pathogen induced necrosis of the ariway epithelial cells leads to mucociliary dysfunction
What are the causes of necrotizing bronchitis/bronchiolitis?
IBR, BRSV, SIV, Herpes, and Histophilus somni
What is degenerative bronchitis/bronchiolitis characterized by?
decreased function of the airway epithelial cells
What causes degenerative bronchitis/bronchiolitis?
Mycoplasma hyopneumoniae and Bordatella bronchiseptica (K9)
What clinical signs are associated with bronchitis/bronchiolitis?
cough (productive), fever and chills, labored breathing (wheezing), and depression
What is the pathogenesis of complete repair to injury to the bronchi/bronchioles?
- degeneration/necrosis with loss of epithelial cells covering the basement membrane
- transient inflammation
- epithelial cell mitosis with cell proliferation
- complete repair
What can result from partial/complete airway obstruction?
bronchiolitis obliterans, atelectasis, emphysema, bronchiecstasis
What is ectasia?
dilation or distention of a tubular structure
What is bronchiectasis?
permanent, abnormal dilation of bronchi
What causes bronchiectasis?
prolonged inflammation
What is the pathogenesis of bronchiectasis?
- severe suppurative bronchitis
- neutrophil lysosomal enzymes weaken/destroy bronchial wall
- dilated, mucus-filled airway with diminished mucociliary clearance
What is the pathogenesis of bronchiolitis obliterans?
- bronchiolar injury
- loss of lining epithelium + lumen filled with fibrinous to suppurative exudate
- fibroblasts migrate in and organize exuate
- partial or complete airway obliteration by fibrous connective tissue
What does partial, valve-like obstruction lead to?
over-inflation (emphysema)
What does complete obstruction of the airways lead to?
atelectasis (alveolar collapse)
What does obstruction that interferes with clearance of the airways lead to?
a preadisposition to bronchopneumonia
What is atelectasis?
alveolar collapse
What is atelectasis neonatorum?
failure of a newborns lung to expand
What can cause atelectasis?
lack of pulmonary surfactant, reduce inspiratory force, obstruction, and compressive (influences within the chest cavity)
What population of animals is reduceed inspiratory force common in?
weak neonates
What are some influences in the chest cavity that can lead to compressive atelectasis?
thoracic effusions and pneumothorax
What does atelectasis look and feel like grossly?
a well demarcated dull red color, the lung is depressed or shrunken compared to surrounding inflated lung with a spongy texture
True or False: When squeezing an atalectic lung you will get fluir or exudate expressed from airways
FALSE
What does atelectasis look like microscopically?
the alveoli are compressed into slits
What is pulmonary edema?
fluid accumulation in the air spaces and/or parenchyma of the lung
What can cause diffuse pulmonary edema?
increased capillary hydrostatic pressure due to left sided heart failure (most common) and low plasma protein oncotic pressure
What can cause non-diffuse pulmonary edema?
increased capillary permeability and obstruction of lymphatic drainage
How does pulmonary edema appear grossly?
The lungs are slightly more red (than in atelectasis), heavy and sligtly swollen. Fluid will ooze from cut surfaces. Clear gluid can distend into the interlobular septae. Frothy fluid will be in the airways and the trachea.
How does pulmonary ededma appear microscopically?
hypocellular amorphus eosinophilic fluid in the alveoli
In balloon terms, what is a normal lung?
a balloon filled with air - very light and no material released when popped
In balloon terms, what is a lung with diffuse pulmonary edema?
a water balloon - much heavier than a normal lung, fluid leaks out of airways when popped
In balloon terms, what is a lung with atelectais?
a sad, old balloon that lost all of its air - the surface may become wrinkled
What is bronchopneumonia?
inflammation of the lung in which exudate accumulates primarily in the bronchi, bronchioles, and alveoli
What is bronchopneumonia most often caused by (general)?
inhaled infectious agents that localize at the bronchiole/alveolar junction
What is emphysema?
an abnormal accumulation of air in the lung
What causes emphysema?
obstruction - air is allowed in but not allowed out
What is alveolar emphysema characterized by?
distension and rupture of alveolar walls - the lungs feel crepitus when palpated
What is bullous emphysema?
if an alveolar lesion becomes confluent and forms a large pocket (greater than 1cm in diameter)
What is interstitial emphysema characterized as?
air ruptures into the interlobar septa
When does interstitial emphysema typically happen in cattle?
in concurrence with respiratory distress or as part of the agonal process because they lack collateral ventilation, have wide interlobular septae, and are prone to developing this lesion
