Pulmonary Circulation Oct13 M1 Flashcards
what prof says about pulmonary arteries
carry partially deoxygenated blood
what prof says about pulmonary veins
carry oxygenated blood
what prof says about bronchial veins
carry partially deoxygenated blood
example of physiological shunt
bronchial veins mostly drain into pulmonary veins rather than venous circulation
pulmonary arteries characteristics
thin wall, diameter changes easily with pressures
pulmonary vascular resistane
resistance in pulmonary circulation
what drives movement in pulmonary circulation
Pa (pulm artery) - PLA (left atrium)
something particular about the pulmonary vascular resistance
decreases as flow increases
why PVR decreases as flow increases
alveolar distension
alveolar recruitment
relationship between pressure and flow across the pulmonary circulation
non-linear. at higher flows, the same pressure gradient produces greater increase in flow (bc resistance lower)
how lung volume affects the resistance of pulmonary vessels
alveolar vessels (septum) get narrower extra-alveolar vessels expand
why extra-alveolar vessels expand with change in pressure
because are attached to surrounding lung tissue so traction force
pulm vessels resistance at volume greater than TLC (intra and extra alveolar)
alveolar vessels: R increases
extra-alveolar: R decreases
extra alveolar vessels resistance at volume lower than FRC
increased
what influences pulmonary vascular resistance (diameter) the most (2)
transmural pressure and lung volume
how pulmonary blood flow varies across the lung + reason
increases as you go from top to bottom and slightly drops at very bottom. Gravity
West’s zones of the lung
Zone 1: top
Zone 2: middle
Zone 3: bottom
what determines blood flow across a lung zone
Pa, Pv and PA
lung zone 1
Palv greater than Pa greater than Pv
lung zone 2
pa greater than p alv greater than pv. waterfall condition
zone 4 of the lung
pa greater than pv greater than palv
what determines flow in lung zones
1: palv-pa
2: pa-palv
3: pa-pv
how pulmonary vessels adapt with certain substances
constrict with hypoxia and low pH
dilate with NO bc relaxes SM
how systemic vessels adapt to hypoxia
dilate and dilate more if low pH
why need to keep alveolar surface dry (and why is this a problem)
for gas exchange
problem bc tendency of fluid in blood to go in alveolar space. (P hydros greater than P oncotic)
what mechanism prevents fluid accumulation in lung interstitium
lymphatics
interstitial vs alveolar pulmonary edema
interstitial: lymphatics can’t handle fluid, excess fluid in pulmonary intersitium
alveolar: interstitial P raised so much it broke alveolar epithelial membranes, fluid leak in alveoli
cardiogenic pulmonary edema
left heart failure so blood pooling in pulmonary circulation
pleural effusion on CXR
one lung’s bottom is higher than the other lung.
