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10 Cards in this Set
- Front
- Back
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What is resistance
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Pressure difference/delta flow = cm H2O/(L/s) -> R=delta P/Q
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What is elastance?
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1/compliance.
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What forms elastic forces in the lung
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1) elastin fibers in interstitum [service side] 2) surface tension of alveolar gas/liquid
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What is surface tension
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A force that tends to reduce surface area (H-bonding)
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Describe the bubble model of lung elastic recoil
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Alevoli are buble-like, per law of laplace, P=2T/R, where T=surface tension. Pressure inside bubble is higher than outside, d/t tension, dependent on R. Surfactant causes t to decrease are R decreases, makes sure bubble will not collapse.
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What kind of resistance is elastic resistance?
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Static: do not measure when air is flowing!
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Describe the relationship of R to surface tension (T) in the lungs
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With larger R, T must be increased. T changes as surfactant is spread out.
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Why does surface tension increase as the lung inflates
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Surfactant molecules spread out, more h-bonds are formed. The bigger the alveoli and end of inspiration, the more surface tension develops to produce elastic recoil
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Describe alveolar surfactant [MoA]
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1) interferes w/ hydrogen bonding 2) becomes concentrated at surface as surface area decreases
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Describe the secretion of alveolar surfactant
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Secreted by Type II cells, release lamellar bodies, which are converted to tubular myelin, and is conveted into a mutlilayer phospholipid surface film
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