2. Alveoli: restrictive venitilatory defect Flashcards
What are the two general functions of alveoli?
Mechanical
Gas Exchange
What are the mechanical functions of alveoli?
Expand on inspiration
Shrink on expiration
Exert outward traction on small airways
How do alveoli benefit gas exchange?
Thin walls- allows more air movement between air and blood
What is a type 2 pneumocyte?
Cell that lines the alveoli of the lung and secretes lung surfactant
What are the factors which affect lung compliance?
Elastin fibres Collagen fibres Surface tension Surfactant Alveolar size Lung volume/history
What creates the tension in the alveolar wall?
Surface tension
Elastin fibres
What is the significance of surfactant?
Reduces surface tension Increases compliance Reduces work of breathing Prevents collapse of small alveoli Stabilises pulmonary capillaries Prevents material egrress into alveoli
effect of increase and decrease of compliance
xx`
How does increase in compliance cause obstruction?
Increase of compliance
Loss of alveolar tethering
Increase of airway resistance
What is the restrictive ventilatory defect?
Reduction of lung volumes
All volumes/capacities reduced
Minute volume perserved early in disease but fails later
What is the forced expiratory manoeuvre?
Fully inflate lungs
Forcefully exhale as fast as possible
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