What is the primary physiological effect of the Haldane effect?

The primary physiological effect of the Haldane effect relates to how the binding of oxygen to hemoglobin influences carbon dioxide transport in the blood. Specifically, the Haldane effect describes how deoxygenated hemoglobin has a greater affinity for carbon dioxide compared to oxygenated hemoglobin.

When hemoglobin releases oxygen to the tissues (a process that occurs at lower partial pressures of oxygen), its configuration changes, allowing it to better bind with carbon dioxide (CO2) produced by cellular metabolism. This phenomenon aids in increasing the efficiency of CO2 uptake in the venous blood returning to the lungs.

Regarding the choice about increased pH and decreased O2 affinity, this is correct in the sense that as CO2 levels increase (from tissues), it leads to the formation of carbonic acid, resulting in a drop in pH (more acidic conditions). Consequently, under increased CO2 concentrations, the affinity of hemoglobin for oxygen decreases - this is known as the Bohr effect.

Thus, the interaction between the Haldane and Bohr effects collectively contributes to the optimal release of oxygen in metabolically active tissues while facilitating the uptake of CO2 for transport back to the lungs. The primary focus of the Haldane effect is on enhancing the