What percentage of carbon dioxide is converted to bicarbonate in red blood cells?

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Multiple Choice

What percentage of carbon dioxide is converted to bicarbonate in red blood cells?

The main concept here is how carbon dioxide is transported in the blood and the reaction that converts most CO2 into bicarbonate within red blood cells. In tissues, CO2 diffuses into circulating RBCs and is rapidly converted by the enzyme carbonic anhydrase: CO2 + H2O forms carbonic acid (H2CO3), which quickly dissociates into bicarbonate (HCO3−) and hydrogen ions (H+). The bicarbonate is then exchanged out of the red blood cell for chloride (the chloride shift) into the plasma, where it becomes a major form of CO2 transport. The hydrogen ions produced bind to hemoglobin, aiding O2 release in tissues (the Bohr effect). Because this conversion to bicarbonate happens inside RBCs and accounts for the majority of CO2 transport, about 70% of CO2 is carried as bicarbonate in plasma after being formed in the red blood cells. The remaining CO2 is carried as carbaminohemoglobin (roughly 20–23%) and dissolved CO2 in plasma (about 7%). So, the percentage converted to bicarbonate in red blood cells is about 70%.

The main concept here is how carbon dioxide is transported in the blood and the reaction that converts most CO2 into bicarbonate within red blood cells. In tissues, CO2 diffuses into circulating RBCs and is rapidly converted by the enzyme carbonic anhydrase: CO2 + H2O forms carbonic acid (H2CO3), which quickly dissociates into bicarbonate (HCO3−) and hydrogen ions (H+). The bicarbonate is then exchanged out of the red blood cell for chloride (the chloride shift) into the plasma, where it becomes a major form of CO2 transport. The hydrogen ions produced bind to hemoglobin, aiding O2 release in tissues (the Bohr effect).

Because this conversion to bicarbonate happens inside RBCs and accounts for the majority of CO2 transport, about 70% of CO2 is carried as bicarbonate in plasma after being formed in the red blood cells. The remaining CO2 is carried as carbaminohemoglobin (roughly 20–23%) and dissolved CO2 in plasma (about 7%).

So, the percentage converted to bicarbonate in red blood cells is about 70%.

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