Defense of the Respiratory System and Response to Injury Flashcards
what makes the lungs a vulnerable site for pathogen entry into the tissues?
minimal thickness of air/blood barrier
what is the common pulmonary response to antigens?
non-inflammatory Th2-mediated
what is pneumonia?
an overgrowth of pathogenic species and loss of normal microbiome organisms followed by host inflammation
what are the major host defenses?
upper respiratory expulsions
mucociliary escalator
neutrophils and macrophages
soluble mucus contents
inflammatory cells
immune response
what microorganism factors can affect the outcome of infectious agents entering the respiratory system?
number of organisms
pathogen virulence
whether or not they are “host adapted”
what does it mean for something to be “host-adapted”?
microorganism has evolved mechanisms to infect only one or a few species
what are the humoral defenses in the lungs against microorganisms?
plasma proteins with antibodies
complement proteins
C-reactive protein
surfactant proteins A and D
pentraxin-3
the mucus blanket functions as a _______________, _______________, _________________ barrier in the airways
mechanical
chemical
biological
what can decrease mucociliary function?
dehydration thickens fluid
atropine
physical airway injury
chemical injury
bacterial attachment to airway cells
viral infection
inflammatory mediators
allergen challenge
what species have intravascular macrophages in small pulmonary capillaries?
horses
ruminants
swine
why does loss of goblet or club cells result in impaired defense mechanism?
airway mucus has factors that can directly injure pathogens, block attachment of bacteria to mucosal surfaces, opsonize bacteria/viruses/fungi
phagocytosis of bacteria by alveolar macrophages results in _____________________
recruitment of neutrophils (chemotactic mediators and diapedesis of neutrophils)
true/false: it is normal to find neutrophils in a TTA or BAL sample
false: if present indicates inflammation and often infection
what does the specific immune response involve?
dendritic cells sampling antigens and migrating through lymph to present to antigen-specific T cells
what cells are involved in the innate immune response?
macrophages
dendritic cells
neutrophils
where does bronchus-associated lymphoid tissue develop?
after birth at sites of particle deposition- airway bifurcations
what cells overlay BALT?
M cells
what synthesizes IgA and why?
committed plasma cells in BALT and submucosa
after stimulation by receptor-mediated uptake and transport through epithelial cells
what is IgA important in?
virus and toxin neutralization, prevention of bacterial and viral attachment to epithelial surfaces, bacterial entrapment/agglutination
where is IgG primarily found in the respiratory tract?
alveolar lining fluid
what does IgG do in the respiratory tract?
opsonization of bacteria to enhance phagocytosis
complement fixation
antibody-dependent cytotoxicity
where do IgA and IgG predominate in the respiratory tract?
IgA in upper
IgG in lower
what do epitheliotropic viruses do?
infect and injure airway or alveolar epithelial cells: loss of integrity of the epithelial barrier and exposure deeper tissues
how can viruses alter the mucociliary excalator?
attach to cilia
alter mucous layer composition
how can viruses impact macrophages?
apoptosis or suppress their phagocytic and bactericidal function
infect: cytotoxic activity directed against
what are two pathogenic microorganisms that target the respiratory epithelium by binding between sialic acid-containing receptors on the ciliary membrane and surface adhesion proteins on the pathogen?
Mycoplasma and Bordatella spp
how long does it take after mechanical trauma for healing to take place?
14 days for epithelium replaced
28 days for full function
what does chronic injury of the epithelium and then continued injury lead to?
goblet cell hyperplasia
squamous metaplasia
when does acute bronchitis take place?
following irritation or airway infection with viruses
parasitic bronchitis is important in ruminants
what is purulent bronchitis characterized by?
neutrophil-rich exudate in airway lumen
what is chronic bronchitis morphologically?
hyperplasia and hypertrophy of goblet cells and mucous glands with increased mucous production
what is bronchiolitis obliterans?
bronchial lumen is obliterated by proliferation of connective tissue and epithelium- dogs
what can happen in swine, sheep, cattle, or rodents with chronic mycoplasma infection?
obstruction due to hyperplasia of the bronchus associated lymphoid tissue
what is bronchiestasis?
sequela of long-term airway infection and inflammation
what are two ways injurious agents can reach the lungs? what results?
airways or circulation
aerogenous or hematogenous pneumonia
what do we see with an aerogenous route of pathogen in quadropeds?
cranioventral pneumonia
what is bronchopneumonia?
extension from distal airways to alveoli
how does pneumonia affect pulmonary function?
reduces area of effective gas exchange
disruption of surfactant
hypoxic vasoconstriction
ventilation-perfusion mismatching
what can chronic pneumonia result in?
fibrosis, bronchiectasis, abscess formation
what can diffuse alveolar injury result from?
severe gram negative sepsis, burn injury, severe tissue trauma, or pancreatitis
what is acute lung injury?
exudation of protein-containing fluid into the alveolar space and recruitment of activated neutrophils into the alveoli
what does the repair phase of injury begin with?
formation of hyaline membranes
how does pulmonary fibrosis lead to restrictive lung diseases?
decreased lung volumes and decreased compliance
diffuse interstitial fibrosis
how is pulmonary arterial hypertension manifested clinically?
increase in pulmonary vascular resistance and increased pulmonary arterial pressure
what is alveolar emphysema?
enlargement of air spaces distal to terminal bronchioles resulting from destruction of alveolar and capillary tissue by proteolytic enzymes
what is interstitial emphysema?
presence of air in connective tissue septa of lung and in subpleural tissue
cattle and swine primarily, otherwise rarely of clinical significance
what is secretory IgA important in?
virus/toxin neutralization
prevention of bacterial and viral attachment to epithelial surface
bacterial agglutination
what can mucus hypersecretion be due to?
increased synthesis and release by goblet or submucosal glands
goblet cell hyperplasia
why does squamous metaplasia occur?
continued injury
in whom can obstruction due to extensive hyperplasia of the bronchus associated lymphoid tissue occur?
swine
sheep
cattle
rodents
chronic mycoplasma infection
what is diffuse alveolar injury often caused by?
gram negative sepsis
burn injury
severe tissue trauma
pancreatitis
what strategies do bacteria that are specialized to invade without prior viral infection use?
surface adhesions
IgA-specific bacterial proteases
bacterial products that inhibit ciliary motion
who is embolic pneumonia common in?
ruminants and swine
what causes the consolidation that occurs with pneumonia?
neutrophil exudates first
neutrophils, lymphocytes, and fibrin
