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CARBON DIOXIDE TRANSPORT IN BLOOD
CO2 TRANSPORT IN BLOOD
CO2
is carried in three forms:
- 90% of CO2
is carried as HCO3–
ions in plasma.
- 5% is carried as dissolved CO2 molecules.
- 5% of CO2
is carried as carbamino compounds, which consist of
CO2 bound to plasma proteins or to hemoglobin within red blood
cells.
CO2 diffuses as a dissolved gas along a gradient of partial pressure from cells to
interstitium to systemic capillary blood plasma. CO2
enters the red blood cells and
combines with H2O to produce H2CO3
in a reaction catalyzed by carbonic
anhydrase
. H2CO3
then dissociates to produce H+ and HCO3
-
ions inside red blood
cells.
CO2 diffuses as a dissolved gas along a gradient of partial pressure from cells to
interstitium to systemic capillary blood plasma. CO2
enters the red blood cells and
combines with H2O to produce H2CO3
in a reaction catalyzed by carbonic
anhydrase. H2CO3
then dissociates to produce H+ and HCO3
-
ions inside red blood
cells.
