What is the normal appearance and function of erythrocytes?

What is the normal appearance and function of erythrocytes?

• A. Large, nucleated cells that store iron.
• B. Nucleated, oval cells that fight infection.
• C. Butterfly-shaped cells that circulate platelets.
• D. Pink, anucleate, biconcave discs that transport oxygen and carbon dioxide.

Answer: (D)

The main concept being tested is how mature red blood cells look and how they function in the bloodstream. Erythrocytes in humans are pink, anucleate, and biconcave discs. The lack of a nucleus in mature RBCs creates more room to pack hemoglobin, the protein that binds oxygen and carbon dioxide. The biconcave shape increases surface area for gas exchange and helps the cells deform as they squeeze through tiny capillaries. Their primary job is to transport oxygen from the lungs to tissues throughout the body and to carry carbon dioxide—the waste product of metabolism—from tissues back to the lungs for exhalation. Other descriptions fit different blood components: large, nucleated cells that store iron would be more like certain immune or precursor cells; nucleated oval cells that fight infection describe white blood cells; butterfly-shaped cells that circulate platelets describe platelets, which are small, anucleate fragments, not the red blood cells.

The main concept being tested is how mature red blood cells look and how they function in the bloodstream. Erythrocytes in humans are pink, anucleate, and biconcave discs. The lack of a nucleus in mature RBCs creates more room to pack hemoglobin, the protein that binds oxygen and carbon dioxide. The biconcave shape increases surface area for gas exchange and helps the cells deform as they squeeze through tiny capillaries. Their primary job is to transport oxygen from the lungs to tissues throughout the body and to carry carbon dioxide—the waste product of metabolism—from tissues back to the lungs for exhalation.

Other descriptions fit different blood components: large, nucleated cells that store iron would be more like certain immune or precursor cells; nucleated oval cells that fight infection describe white blood cells; butterfly-shaped cells that circulate platelets describe platelets, which are small, anucleate fragments, not the red blood cells.