Respiratory Pathology - lecture 1 Flashcards
What are the three parts of the respiratory tract?
- conducting system
- transitional system
- exchange system
What are the differences in mucosal lining of the 3 systems of the resp tract?
conducting is lined by ciliated epithelium and goblet cells
transitional is lined by ciliated and secretory cells, no goblet cells
exchange is lined by pneuomocytes (type 1 and type 2)
what’s the difference between type 1 and 2 pneymocytes?
type 1 = membranous; thin cells that make up blood-air barrier with capillary endothelium + basement membrane
type 2 = cuboidal cells, make surfactant
how is the nasal cavity divided?
turbinates or conchae which are curled shelves of bone covered in mucous membrane
which species gets clinical sinus problems more than others?
horse
what are the five main functions of the respiratory system?
- air conduction (move air)
- air conditioning (heat + moisture)
- air filtration and immune defense
- smell
- vocalization
name three non-specific defense mechanisms of the resp system
- air filtration
- mucociliary clearance system
- coughing & sneezing
name three specific defense mechanisms of the resp system
- pulmonary alveolar macrophages & intravascular monocytes in lung
- antibodies
- mucus lining absorption of soluble gases
what’s choanal atresia?
failure of formation of the communication between nasal cavity and nasopharynx
- is usually bilateral
- common in camelids
what are congenital components of brachycephalic airway syndrome (BAS)?
- stenotic nares
- elongated soft palate (beyond epiglottis and into larynx)
- tracheal/laryngeal hypoplasia
how do the congenital components of BAS lead to airway obstruction?
any congenital component –> increased respiratory effort –> secondary malformations –> further narrow and compromise upper resp tract –> noisy breathing, inspiratory dyspnea –> airway obstruction
- laryngeal saccules, everted tonsils, hypertrophied and folded pharyngeal mucosa, laryngeal edema and collapse, or tracheal collapse
what happens in tracheal collapse?
abnormal tracheal cartilage –> dorsoventral flattening of trachea –> abnormal tracheal rings (D instead of C) and dorsal tracheal muscle is wide & floppy –> honking cough and exercise intolerance
what kind of problems can happen with epiglottic hypoplasia in horses?
epiglottic entrapment (aryepiglottal folds are above dorsal epiglottic surface)
dorsal displacement of the soft palate (caudal free margin of soft palate is dorsal to epiglottis = obstructed airway)
progressive ethmoid hematomas: who gets them and from where do they arise?
older horses, thoroughbred and arabians are predisposed
arise from ethmoid turbinates
nasopharyngeal polyps: who gets them and from where do they arise?
common in young cats and can occur in horses
in cats: from middle ear or auditory tube or mucosal lining of turbinates
in horses: from nasal mucosa
what do you see grossly and histologically with equine laryngeal paralysis?
gross: left sided denervation atrophy of cricoarytenoid muscles
histo: progessive loss of fibres and demyelination
what side do we usually see laryngeal paralysis in horses?
left side
when can we see bilateral laryngeal paralysis?
- anesthesia
- hepatic encephalopathy
what are 2 big differences between equine and canine laryngeal paralysis?
- dogs usually have bilateral paralysis
- dogs have associated generalized neuromuscular disorder
can laryngeal & tracheal edema happen in any domestic species?
YES! but secondary to acute inflammatory process like anaphylaxis, atypical interstitial pneumonia (cattle), or edema disease (pigs)
what’s honker syndrome?
tracheal edema and hemorrhage syndrome in cattle
rapid breathing + increased pressure in trachea during inspiration –> mechanical injury to tracheal mucosa –> inflammation, hemorrhage, edema –> tissue protrudes into airway –> repeat
list the 5 types of inflammation in the upper resp tract
- serous rhinitis
- catarrhal
- purulent / suppurative
- fibrinous
- granulomatous
what do we get in purulent/suppurative inflammation?
- neutrophilic exudate
- boston creme donut
- mucosal necrosis
- associated bacterial (or fungal) infection
what do we get in fibrinous inflammation?
- suppurative + increased vascular permeability
- runny scrambled eggs
- may form fibrinonecrotic membranes (= necrotic debris, fibrin, suppurative inflammation forming pseudomembrane that adheres to the underlying ulcerated surface)
- bacterial or fungal infection
what do we get in granulomatous inflammation?
- usually chronic inflammation
- cottage cheese or stiff cream cheese
- fungal infection or mycobacteria