Skip to main content
Fig. 1 | Critical Care

Fig. 1

From: Pathophysiology and clinical implications of the veno-arterial PCO2 gap

Fig. 1

Physiology of CO2 production and transport. In cells, CO2 is produced (in mitochondria) as a byproduct of substrate oxidation. Under anaerobic conditions, CO2 is generated in small amounts, as the results of HCO3 buffering of protons released by lactic acid and the hydrolysis of ATP. CO2 diffuses into the interstitial tissues and then into capillaries, where it is transported as dissolved CO2 in plasma (in equilibrium with the PCO2), bound to hemoglobin as carbamino-hemoglobin (HbCO2) in red blood cells (RBC), and as HCO3, following the reaction of CO2 with H2O within RBC, a reaction catalyzed by carbonic anhydrase to form HCO3 and H+. HCO3 exits the RBC in exchange with chloride anions (Cl), whereas protons are buffered by hemoglobin, forming HbH

Back to article page