Final answer:
Carbon dioxide is transported in the blood through dissolution in plasma, binding to hemoglobin to form carbaminohemoglobin, and primarily via the bicarbonate buffer system after conversion by carbonic anhydrase. About 85% of CO2 transport occurs through the bicarbonate ion method, enabling efficient CO2 removal from the body.
Step-by-step explanation:
Carbon dioxide (CO2) is transported in the blood via three primary mechanisms:
- Dissolved directly in blood plasma
- Bound to hemoglobin within red blood cells to form carbaminohemoglobin
- Converted into bicarbonate ions through a series of reactions involving carbonic acid.
About 5 to 7 percent of CO2 is dissolved in the plasma. An intermediate amount, approximately 10 percent, binds to hemoglobin. However, the majority of CO2, around 85 percent, is carried as part of the bicarbonate buffer system. Within red blood cells, the enzyme carbonic anhydrase catalyzes the conversion of CO2 into carbonic acid (H2CO3), which then dissociates into bicarbonate (HCO3-) and hydrogen ions (H+). This reaction is essential for CO2 transport as it allows for a continuous diffusion of CO2 into the blood. The bicarbonate ions are exchanged for chloride ions (Cl-), known as the chloride shift, and transport CO2 to the lungs where the process is reversed to eliminate CO2 from the body.