Which of the following will shift the O2 dissociation curve to the left?

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Multiple Choice

Which of the following will shift the O2 dissociation curve to the left?

Shifting the oxygen–hemoglobin dissociation curve to the left means hemoglobin has a higher affinity for oxygen, so at the same partial pressure of oxygen, more oxygen stays bound to Hb and loading in the lungs is favored while unloading in tissues becomes harder. Alkalosis raises blood pH and lowers hydrogen ion concentration, which stabilizes the oxygenated form of hemoglobin and increases its affinity for O2. This produces a leftward shift. In practice, that means oxygen uptake in the lungs is improved, but delivery to tissues can be less efficient if unloading is impeded. Anemia doesn’t change the curve’s position—it lowers the overall oxygen-carrying capacity but not Hb’s affinity. Hypercapnia and hyperthermia both promote rightward shifts, increasing oxygen release in tissues by decreasing Hb’s affinity.

Shifting the oxygen–hemoglobin dissociation curve to the left means hemoglobin has a higher affinity for oxygen, so at the same partial pressure of oxygen, more oxygen stays bound to Hb and loading in the lungs is favored while unloading in tissues becomes harder. Alkalosis raises blood pH and lowers hydrogen ion concentration, which stabilizes the oxygenated form of hemoglobin and increases its affinity for O2. This produces a leftward shift. In practice, that means oxygen uptake in the lungs is improved, but delivery to tissues can be less efficient if unloading is impeded. Anemia doesn’t change the curve’s position—it lowers the overall oxygen-carrying capacity but not Hb’s affinity. Hypercapnia and hyperthermia both promote rightward shifts, increasing oxygen release in tissues by decreasing Hb’s affinity.

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