Why left shift seen with co and rt shift with CO2
Why co poisoning causes anemic hypoxia
Co is having the highest afnity to bind with hemoglobin and once it binds it hinders the release of O2 to tissues
And why rt shift with CO2…CO2 also binds to hb with more affinity na!
see this image attached: it shows that In CO poisoning hypoxia is similar to anemic hypoxia because suppose 50% of Hb has atleast one mol of CO: now it will never going to let it’s Oxygen leave its molecule at tissue level: Now this Hb is a wastage. This behaves like anemic hypoxia where actually Total Hb is around 6-7gm% but here total Hb is around 12-14gm% but Hb which is normally functioning is Only that 50% which is not having even single mol of CO so here EFFECTIVE Hb becomes again 6-7gm% : so CO poisoning cause anemic Hypoxia
It’s all about the affinity of Hb(FOR OXYGEN). Anything which decreases this affinity will shift curve to right and anything which increases this affinity will shift curve to left. pCO2 and Low pH anytime will itself Decrease the affinity of Hb FOR O2 that’s why Unloading of O2 happens at tissues physiologically; so pCO2 causes right shift.
But CO is something diff because it binds with Hb with 240times affinity more than O2 and this cause ALLOSTERIC change in Configuration of Hb such that all those Hb molecules which have even a single molecule of CO with other 3 mols of O2: all those Hb fail to unload even thEse 3 molecules of O2 at level of tissues causing Hypoxia. This means that binding of even a single mol of CO will increase the affinity of Hb fOR OXYGEN such that it will not unload even those Oxygen that it have so cause LEFT shift