Hi everyone. I'm having a little trouble understanding the "loading" and "unloading" of CO2 and O2 in the blood at the tissues and lungs. I thought I had it down, but when I tried to summarize it to my prof, she ripped me apart.
Do I have this down right?
In the erythrocyte, the bicarbonate reaction is as such CO2+H2O<-->H2CO3<-->H+ + HCO3-
The blood reaches the systemic tissues with Hb highly saturated with O2. The partial pressure of CO2 is lower in the erythrocyte than in the surrounding tissues, so CO2 diffuses across into the erythrocyte, combines with H2O and shifts the equilibrium to the right. More H+ and HCO3- are produced. An abundance of H+ means that it can binds to the oxyhemoglobin, lowering hemoglobin's affinity for O2 and causing an "unloading" of O2 into the surrounding rissue. The haldane effect allows the now H+ bound hemoglobin (deoxyhemoglobin) to bind more CO2 as carbamino hemoglobin.
Now, the deoxygenated blood reaches the lungs. At the alveolar surface, a higher pO2 diffuses across and binds the deoxyhemoglobin (obviously, more and more binds due to the cooperative binding property), reducing its affinity for H+. H+ is unloaded, causing the equilibrium to shift to the left, producing excess CO2 and H2O, which diffuse across to the alveolus and are thus expelled. Also, the affinity of hemoglobin for CO2 is reduced when O2 is bound to it, so the CO2 bound in carbamino hemoglobin is also released.
I'm sorry if asking this question makes me seem like an idiot, but anyone who would be willing to help me understand this better would be doing me a huge service.
Many thanks.
Never mind. Just got it. Sorry for wasting everyone's time.
Do I have this down right?
In the erythrocyte, the bicarbonate reaction is as such CO2+H2O<-->H2CO3<-->H+ + HCO3-
The blood reaches the systemic tissues with Hb highly saturated with O2. The partial pressure of CO2 is lower in the erythrocyte than in the surrounding tissues, so CO2 diffuses across into the erythrocyte, combines with H2O and shifts the equilibrium to the right. More H+ and HCO3- are produced. An abundance of H+ means that it can binds to the oxyhemoglobin, lowering hemoglobin's affinity for O2 and causing an "unloading" of O2 into the surrounding rissue. The haldane effect allows the now H+ bound hemoglobin (deoxyhemoglobin) to bind more CO2 as carbamino hemoglobin.
Now, the deoxygenated blood reaches the lungs. At the alveolar surface, a higher pO2 diffuses across and binds the deoxyhemoglobin (obviously, more and more binds due to the cooperative binding property), reducing its affinity for H+. H+ is unloaded, causing the equilibrium to shift to the left, producing excess CO2 and H2O, which diffuse across to the alveolus and are thus expelled. Also, the affinity of hemoglobin for CO2 is reduced when O2 is bound to it, so the CO2 bound in carbamino hemoglobin is also released.
I'm sorry if asking this question makes me seem like an idiot, but anyone who would be willing to help me understand this better would be doing me a huge service.
Many thanks.
Never mind. Just got it. Sorry for wasting everyone's time.
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