Which of the following causes a rightward shift in the oxygen dissociation curve?

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Multiple Choice

Which of the following causes a rightward shift in the oxygen dissociation curve?

Hemoglobin’s oxygen affinity changes with conditions that affect the state of Hb. A rightward shift means Hb releases oxygen more readily to tissues, which happens when factors lower Hb’s affinity for O2 (higher P50). The CO2/acid–base balance is a key driver: increased CO2 raises H+ (lower pH) in the blood, stabilizing the deoxygenated form of Hb and promoting O2 release. This Bohr effect explains why higher carbon dioxide pressure shifts the curve to the right. Hypothermia lowers metabolic heat and tends to stabilize Hb in its high-affinity form, shifting the curve left. Alkalosis raises pH, increasing Hb’s affinity for O2 and also shifting left. Decreased production of 2,3-DPG reduces a modulator that normally lowers Hb’s O2 affinity, contributing to a leftward shift as well. Therefore, increased carbon dioxide pressure best explains a rightward shift in the curve.

Hemoglobin’s oxygen affinity changes with conditions that affect the state of Hb. A rightward shift means Hb releases oxygen more readily to tissues, which happens when factors lower Hb’s affinity for O2 (higher P50). The CO2/acid–base balance is a key driver: increased CO2 raises H+ (lower pH) in the blood, stabilizing the deoxygenated form of Hb and promoting O2 release. This Bohr effect explains why higher carbon dioxide pressure shifts the curve to the right.

Hypothermia lowers metabolic heat and tends to stabilize Hb in its high-affinity form, shifting the curve left. Alkalosis raises pH, increasing Hb’s affinity for O2 and also shifting left. Decreased production of 2,3-DPG reduces a modulator that normally lowers Hb’s O2 affinity, contributing to a leftward shift as well.

Therefore, increased carbon dioxide pressure best explains a rightward shift in the curve.

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