CO2 Transport
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- Topic Anchor: CO2 Transport
- Gaseous CO2 in RBCs is converted into carbonic acid and bicarbonate to allow water-soluble transport in blood
- CO2 + H2O <--> H2CO3 <--> HCO3— + H+
- CO2 mainly carried as bicarbonate ion in blood
- Catalyzed by carbonic anhydrase
- pCO2 drives CO2 transport
- In tissues
- High pCO2 generated by respiration of tissues
- drives reaction forward
- Conversion of CO2 → bicarbonate
- Bicarbonate diffuses into plasma, allowing reaction to continue
- High pCO2 generated by respiration of tissues
- In lungs
- Low pCO2 due to exhalation
- drives the reaction backward
- Conversion of bicarbonate → CO2
- Bicarbonate diffuses from plasma into RBC to supply this reaction
- Low pCO2 due to exhalation
- In tissues
- Used to buffer pH of blood
- When blood is too acidic, reverse reaction is favored to increase pH
- When blood is too basic, forward reaction is favored to decrease pH
- Gaseous CO2 in RBCs is converted into carbonic acid and bicarbonate to allow water-soluble transport in blood