Question

In what form is most of the carbon dioxide present in our blood transported? Group of answer choices As carbon dioxide dissolved directly in blood plasma As CO2 linked to heme groups on hemoglobin's beta globulins As bicarbonate ions present in blood plasma As carbonic anhydrase attached to hemoglobin's alpha strands As carbon monoxide bound by hemoglobin in erythrocytes As free hydrogen ions found in blood plasma

Answer 1

As bicarbonate ions present in blood plasma

Step-by-step explanation:

Most carbon dioxide produced by tissues (approximately 75%) is transported in the blood to the lungs as bicarbonate ions (HCO₃⁻).

The chemical equilibrium is:

CO₂ + H₂O ↔ H₂CO₃ ↔ H⁺ + HCO₃⁻

carbonic acid

In the lungs, the conversion is reversed, so CO₂ diffuses from the blood into the alveoli and then it's exhaled.

Although most CO₂ is reversibly converted to bicarbonte, approximately 5% is simply dissolved in the blood plasma and about 20% is bound with hemoglobin.

This conversion to bicarbonate ions keeps the partial pressure of CO₂ in blood plasma low, facilitating its diffusion away from the tissues.