-In the hemoglobin- $\mathrm{O}_{2}$ dissociation curves shown above, the shift from curve A to curve B could be caused by

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[IV C 1; Figure 4.8]. Strenuous exercise increases the temperature and decreases the $\mathrm{pH}$ of skeletal muscle; both effects would cause the hemoglobin- $\mathrm{O}_{2}$ dissociation curve to shift to the right, making it easier to unload $\mathrm{O}_{2}$ in the tissues to meet the high demand of the exercising muscle. 2,3-Diphosphoglycerate (DPG) binds to the $\beta$ chains of adult hemoglobin and reduces its affinity for $\mathrm{O}_{2}$, shifting the curve to the right. In fetal hemoglobin, the $\beta$. chains are replaced by $\gamma$ chains, which do not bind 2,3-DPG, so the curve is shifted to the left. Because carbon monoxide (CO) increases the affinity of the remaining binding sites for $\mathrm{O}_{2}$, the curve is shifted to the left.

-In the Hemoglobin- O2\mathrm{O}_{2}O2​ Dissociation Curves Shown Above, the Shift from Curve a to from Curve

-In the Hemoglobin- $\mathrm{O}_{2}$ Dissociation Curves Shown Above, the Shift from Curve a to from Curve