Pathology of the Lung Flashcards
Pulmonary Congestion & Oedema is caused when…
there is a slow, steady flow of liquid into interstitium as the pressure in the interstitium becomes less than that of the pressure in the alveolus, which then drains away into the LN’s
Oedema occurs under what two conditions?
*increase in capillary HP
*increased permeability of alveolar-capillary wall
What is the etiology of pulmonary congestion & oedema?
*Passive congestion: increased intravascular HP (LSHF)
*Active hyperemia: permeability oedema where there is injury to alveolar-capillary wall
pulmonary congestion & oedema may lead to…
respiratory failure
How does pulmonary congestion & oedema lead to respiratory failure?
*VQ mismatch
*oxygen doesn’t diffuse readily through the edematous fluid
*hypoxic damage to the alveolar walls increases permeability
how can pulmonary congestion & oedema lead to bacterial pneumonia?
the fluid can be readily invaded by bacteria and take hold
What are the 3 main abnormalities of inflation of the lungs?
*atelectasis: incomplete expansion of lungs
*Overinflation
*Emphysema
What is neonatal atelectasis?
Defective surfactant production or aspiration of amniotic fluid
What is acquired atelectasis?
Fully expanded lungs that collapse due to either airway obstruction or external compression
Explain Neonatal atelectasis when the there is an immaturity and defective surfactant production.
High surface tension at air-liquid interface:
*draws proteinaceous fluid into alveolar spaces which deposits as hyaline membrane (neonatal hyaline membrane dz)
*causes alveoli to collapse on expiration
*tension & shear stresses acting on collapsed alveolar walls during reinflation attempts damages type I pneumocytes
Explain neonatal atelectasis when there is aspiration of amniotic fluid at birth.
- Amniotic fluid physically obstructs airways and interferes w/ surfactant production/fxn
Neonatal hyaline membrane dz affects…
*foal, pup, calf, lamb
Acquired atelectasis (lung collapse) is…
*complete obstruction of the airways where the trapped air can be resorbed
*Compressive due to mass or fluid/air compressing the lung parenchyma
Overinflation of the lung occurs when…
air spaces distal to terminal bronchiole enlarged but the walls are not damaged therefore making it reversible
Emphysema is when…
air spaces are enlarged with irreversible damage to alveolar walls
