What is the primary function of red blood cells?

What is the primary function of red blood cells?

• A. Transport carbon dioxide
• B. Clot blood
• C. Transport oxygen
• D. Fight infection

Answer: (C)

Red blood cells are specialized to deliver oxygen to tissues throughout the body. This relies on hemoglobin, a protein inside the cells with iron that binds oxygen reversibly. In the lungs, oxygen concentration is high, so oxygen binds to hemoglobin. As blood reaches tissues where oxygen is scarce and carbon dioxide is high, hemoglobin releases the oxygen to meet cells’ needs. This oxygen delivery is the primary job of red blood cells. RBCs also help with carbon dioxide transport and acid–base balance, but that role is secondary. Carbon dioxide is mostly carried back to the lungs as bicarbonate in the plasma, produced by carbonic anhydrase inside red blood cells, with a portion also bound to hemoglobin or dissolved. While some CO2 transport occurs within red blood cells, the central, defining function is moving oxygen from lungs to tissues. The other options describe functions of platelets (clotting) and white blood cells (fighting infection).

Red blood cells are specialized to deliver oxygen to tissues throughout the body. This relies on hemoglobin, a protein inside the cells with iron that binds oxygen reversibly. In the lungs, oxygen concentration is high, so oxygen binds to hemoglobin. As blood reaches tissues where oxygen is scarce and carbon dioxide is high, hemoglobin releases the oxygen to meet cells’ needs. This oxygen delivery is the primary job of red blood cells.

RBCs also help with carbon dioxide transport and acid–base balance, but that role is secondary. Carbon dioxide is mostly carried back to the lungs as bicarbonate in the plasma, produced by carbonic anhydrase inside red blood cells, with a portion also bound to hemoglobin or dissolved. While some CO2 transport occurs within red blood cells, the central, defining function is moving oxygen from lungs to tissues. The other options describe functions of platelets (clotting) and white blood cells (fighting infection).