Which three factors affect the position of the oxygen dissociation curve?

Which three factors affect the position of the oxygen dissociation curve?

• A. pH, CO2, Temperature
• B. Oxygen partial pressure alone
• C. Haematocrit
• D. Platelet count

Answer: (A)

The position of the oxygen dissociation curve shows how readily hemoglobin releases oxygen and is shifted by conditions that change hemoglobin’s affinity for oxygen. A rightward shift means Hb has lower affinity, so it unloads oxygen more readily to tissues; a leftward shift means higher affinity, keeping oxygen bound more tightly. pH and CO2 drive the Bohr effect: when CO2 levels rise and pH falls (more H+), hemoglobin’s affinity for oxygen decreases, shifting the curve to the right. Temperature also influences affinity—higher body temperature reduces Hb’s oxygen affinity, causing a rightward shift. Therefore, the three factors that affect the curve’s position are pH, CO2, and temperature. Oxygen partial pressure alone describes the curve but doesn’t move it; hematocrit changes oxygen carrying capacity rather than Hb’s affinity, and platelet count has no effect on the curve.

The position of the oxygen dissociation curve shows how readily hemoglobin releases oxygen and is shifted by conditions that change hemoglobin’s affinity for oxygen. A rightward shift means Hb has lower affinity, so it unloads oxygen more readily to tissues; a leftward shift means higher affinity, keeping oxygen bound more tightly. pH and CO2 drive the Bohr effect: when CO2 levels rise and pH falls (more H+), hemoglobin’s affinity for oxygen decreases, shifting the curve to the right. Temperature also influences affinity—higher body temperature reduces Hb’s oxygen affinity, causing a rightward shift. Therefore, the three factors that affect the curve’s position are pH, CO2, and temperature. Oxygen partial pressure alone describes the curve but doesn’t move it; hematocrit changes oxygen carrying capacity rather than Hb’s affinity, and platelet count has no effect on the curve.