Flashcards in 1. Resp Physiology Deck (19):
have cartilage, supply lobes and segments
no cartilage, held open by surroundings
inspiratory musc have to overcome what (2 things)?
elastic recoil of lungs and flow resistance of system
formula for compliance?
compliance = dV/dP (volume, pressure)
formula for resistance?
R = P1-P2/flow (driving pressure/flow)
resistance decr or incr as lung vol expands?
decr because lung tissue pulled open
most of resistance is in large or small airways?
large: due to decr cross-section
what force drives passive expiration?
why does flow limitation occur?
because airways are collapsible rather than rigid, there is a pressure at which they will collapse
If Pcrit = neg, what does that mean? what about Pcrit = pos?
if neg: airway is strong/supported, would need outside pressure to collapse
if pos: airway is collapsed, like putting a rubber band around it
why do airways have a tendency to collapse with exhalation?
what is the formula for max possible flow?
Vmax = Pelastic-Pcrit/Rupstream
three ways to reduce Vmax
reduce lung elastic recoil (Pelastic)
incr Pcrit (rubber band)
incr R upstream with swelling, mucus, bronchitis
2 ways to incr residual volume
emphysema: lose elasticity. causes flow to end sooner, incr RV
asthma: incr Pcrit, flow decreases sooner, incr RV
interstitial lung disease: inc or decr lung tissue elastic recoil?
emphysema: inc or decr lung tissue elastic recoil?
fluid-filled lung: incr or decr surface forces at alveoli?
surfactant deficiency: incr or decr surface forces at alveoli?