Acclimatization to high-altitude hypoxia via erythropoiesis

Steps:

• Low oxygen at altitude triggers hypoxia, detected by kidneys.
• Kidneys release erythropoietin (EPO) hormone.
• EPO stimulates bone marrow to produce more red blood cells (RBCs).
• Increased RBCs enhance oxygen transport to tissues.

Why C is correct:

• Erythropoiesis, the process of RBC production, increases RBC count per mm³ to compensate for lower oxygen availability, as defined by physiological response to hypoxia.

Why the others are wrong:

• A: Hemoglobin concentration per RBC remains constant; total hemoglobin rises only due to more RBCs.
• B: Each hemoglobin molecule's oxygen-binding sites (four per molecule) do not increase.
• D: Hemoglobin's oxygen release rate is regulated by tissue pH and CO2, not directly by altitude acclimatization.

Final answer: C