What effect does a decrease in pH have on the hemoglobin-oxygen dissociation curve?

A decrease in pH, which indicates an increase in acidity (more hydrogen ions), results in a shift of the hemoglobin-oxygen dissociation curve to the right. This phenomenon is known as the Bohr effect. When pH decreases, hemoglobin's affinity for oxygen decreases, meaning that hemoglobin is less likely to hold onto oxygen and will release it more readily to the tissues. This is crucial during conditions such as exercise or in metabolically active tissues where carbon dioxide production is high, leading to a drop in pH due to increased acidity.

With this rightward shift, it allows for greater oxygen unloading to tissues where it is most needed. In summary, a decrease in pH shifts the curve to the right and decreases hemoglobin's affinity for oxygen, enabling effective oxygen delivery under physiological conditions.