Diffusion of GasesGas exchange between alveoli and blood•Oxygen diffuses into the blood•Carbon dioxide diffuses into the alveoliDiffusion across the alveolar membrane•Thickness•Surface area
Diffusion of GasesPartial pressures: what are the gradients?
Diffusion of GasesHenry’s law: at an air water interface, the amount of gas which will dissolve is determined by the partial pressure of the gases in the air and the solubility in water•O2not very soluble in water•CO2more soluble in waterO2= 100 mm Hg * 0.03 mL O2/L/ mm HgO2= 0.3 mL O2/ 100 ml blood
OxygenOxygen content in blood•Plasma alone vs. Plasma with hemoglobin•PO2vs. O2ContentHemoglobin•Binds four O2moleculesCooperative binding•Deoxyhemoglobin (Hb)•Oxyhemoglobin (HbO)
OxygenOxygen transport:1. Dissolved2.Bound to Hb
OxygenHemoglobin saturation = O2bound to HbMaximal binding capacity of Hb to O2PO2determines binding affinity•High at lungsSafety net in Hb situation
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- Spring '18