Diffusion and Perfusion Flashcards
Why does oxygen bind to hemoglobin for transport?
Low solubility giving low dissolved oxygen content, hemoglobin allows more to be transported
What factors influence diffusion from alveoli?
Pressure gradient across membrane, surface area, and membrane thickness.
How does interstitial lung disease affect diffusion?
Increases wall thickness
How does emphysema affect diffusion?
Decreases surface area
What factors regulate perfusion?
O2 tension, other chemicals (thromboxane and prostacyclin), capillary recruitment, and gravity.
What is a shunt?
Perfusion with no ventilation (reverse of deadspace)
How is V/Q mismatch regulated?
High V/Q: PACO2 drops increasing resistance and ventilation.
Low V/Q: low PAO2 causes hypoxic vasoconstriction and lowering perfusion.
