What factor contributes to the release of oxygen from hemoglobin near tissues?

The release of oxygen from hemoglobin near tissues is primarily facilitated by a decreased pH, a phenomenon known as the Bohr effect. When tissues are metabolically active, they produce carbon dioxide and lactic acid, which leads to a reduction in the pH of the surrounding environment. The lower pH causes hemoglobin to change its conformation, reducing its affinity for oxygen and promoting the release of oxygen where it is needed most.

This relationship between pH and oxygen release is crucial because it allows for efficient delivery of oxygen to tissues that are actively engaged in cellular respiration and require more oxygen for energy production. Additionally, higher concentrations of carbon dioxide, which correlate with lower pH, also enhance this process, further driving oxygen release from hemoglobin.

In this context, options that suggest increased pH or higher oxygen pressure do not facilitate oxygen release in the same manner. An increased pH would actually enhance hemoglobin's affinity for oxygen, making it less likely to release it into the tissues. Similarly, a higher partial pressure of oxygen would favor oxygen binding to hemoglobin rather than its release. Lower carbon dioxide concentration would also result in a higher pH, again promoting oxygen binding rather than release. Thus, the decreased pH is a key