Gas Transport 2 Osmo1 - The transport of O2 and CO2 in the...

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The transport of O 2 and CO 2 in the blood (con't) Maternal vs. fetal hemoglobin differences in the P 50s of maternal and fetal Hb ensure that oxygen is available to the fetus at 40 torr, maternal Hb is 60% bound to O 2 ; fetal Hb is 80% bound--which one has the greater affinity (lower P 50 )? thus, there is always an O 2 pressure gradient favoring diffusion of O 2 from the mother's blood stream into the fetal blood stream Why is the Hb dissociation curve sigmoid? because Hb is actually a tetramer of 4 Hb subunits the affinity of the first subunit for O 2 is low, but once it binds the affinity of the remaining three subunits is increased, so they bind O 2 relatively easily this appears as the steep part of the dissociation curve note that the same is true when talking about the release of the first oxygen, as the surrounding O 2 pressure falls how would this facilitate off-loading of O 2 at the tissues?
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Gas Transport 2 Osmo1 - The transport of O2 and CO2 in the...

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