What is the Bohr effect in the lungs primarily responsible for?

• A. Increased O2 affinity
• B. Decreased O2 release to tissues
• C. Promoting O2 release to tissues
• D. Increased CO2 retention

Answer: (C)

The Bohr effect describes how the affinity of hemoglobin for oxygen decreases in the presence of increased levels of carbon dioxide (CO2) and hydrogen ions (H+), a phenomenon that primarily occurs in the tissues rather than the lungs. In the lungs, where the concentration of oxygen is high and CO2 is being expelled, the opposite effect is observed. The higher oxygen levels lead to an increased affinity of hemoglobin for oxygen, allowing for more effective oxygen uptake.

However, in the context of the tissues, where there is greater production of CO2 and the release of H+ ions due to cellular metabolism, hemoglobin's affinity for oxygen decreases. This facilitates the release of oxygen from hemoglobin to the tissues that need it most urgently. Therefore, the Bohr effect is critically responsible for promoting the release of oxygen to tissues, ensuring that the areas with high metabolic activity receive an adequate supply of oxygen, which is crucial for energy production and maintaining cellular function.