Transport Of O2 & CO2 Flashcards
How are erthyrocytes adapted to transport oxygen
How does oxyhaemoglobin form
Oxygen binds to haemoglobin
4O2 + Hb <-> Hb(O2)4
Carrying oxygen process
E.g.
Entering capillaries -> moving to bind -> etc
Normal (adult) oxygen dissociation curve
Fetal Hb O2 affinity curve
Whats the bohr effect
As the partial pressure of CO2 rises, at (higher CO2 partial pressures), haemoglobin gives oxygen up more easily
As a result of Bohr shift
1. Hb gives up its oxygen more readily in…
2. In the lungs where the proportion of CO2 in the air is relatively low…
1… active tissues with a high pressure of CO2
2… oxygen binds to the Hb easily
How is CO2 transport
75-85% converted into HCO3- ions jn the cytoplasm of RBC’s
5% of CO2 is carried dissolved in the plasma
10-20% combines with amino grouos in the polypeptide chains of globin to form carbamino haemoglobin
What happens to the CO2 converted into HCO3- ions
Where does CO2 react to form H2CO3 & then H+ and HCO3-
Normwlly occurs slowly in blood plasma, but the RBC’s cytoplasm has high levels of carbonic anhydrase to catalyse the CO2 and H2O reaction
Whats the chloride shift?
When HCO3- ions move out of the RBC’s via diffusion down a conc gradient
-> as a result, negative Cl- ions move inside the RBC’s to maintain the cells electrical balance
Why is it good to remove the CO2 and convert it to HCO3-
Steep conc gradient for CO2 to diffuse is maintained
How does Hb act as a buffer
To prevent changes in pH, it accepts free H+ in reversible reactions to form haemoglobinic acid
When the blood concentration reaches the lung tissue where theres a low concentration of carbon dioxidezc carbonic anhydrase does what?
Catalyse the reverse reaction, breaking carbonic acid down into CO2 & H2O
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