Which of the following contributes the least percentage to carbon dioxide transport?

The correct answer relates to how carbon dioxide (CO2) is transported in the bloodstream, primarily through three mechanisms: dissolved in blood plasma, as bicarbonate, and as carbamino compounds. Among these, the form “dissolved in blood plasma” accounts for a relatively small percentage of CO2 transport, typically around 5-10%.

In contrast, the bicarbonate form is the dominant means of transport, accounting for about 70% of CO2 transport. This occurs when CO2 reacts with water in the presence of the enzyme carbonic anhydrase, forming bicarbonate ions that are then carried in the plasma. Similarly, carbamino compounds, which are formed from CO2 binding to proteins (mainly hemoglobin), make up approximately 20-25% of carbon dioxide transport.

Myoglobin, while involved in oxygen storage and transport in muscle tissue, does not contribute significantly to carbon dioxide transport. Thus, it is not considered in this question regarding the primary forms of CO2 transport.

Understanding these percentages and mechanisms is critical when evaluating how the body handles CO2, especially during activities that increase its production, such as exercise.