Question

The Bohr effect aids in the release of oxygen from Hb under which of the following conditions?

A. When the concentration of BPG is decreased in the blood.

B. When the temperature of the body rises during exercise.

C. When the concentration of BPG is increased in the blood.

D. Low pH due to the production of CO₂ and lactic acid in the muscle tissue.

Answer 1

The correct options are C and D

Explanation: Hemoglobin exhibits sigmoid-like kinetics. In selectively binding to deoxyhemoglobin, BPG stabilizes the T state conformation, making it harder for oxygen to bind hemoglobin and more likely to be released to adjacent tissues. BPG is part of a feedback loop that can help in preventing tissue hypoxia in conditions where it is most likely to occur. Conditions of low tissue oxygen concentration such as high altitude (BPG levels are higher in those acclimated to high altitudes), airway obstruction, or congestive heart failure will tend to cause RBCs to generate more BPG because changes in pH and oxygen modulate the enzymes that make and degrade it. The accumulation of BPG decreases the affinity of hemoglobin for oxygen. Hence, this mechanism increases oxygen release from RBCs under circumstances where it is needed most. This release is potentiated by the Bohr effect, in which hemoglobin's binding affinity for oxygen is also reduced by a lower pH and high concentration of carbon dioxide. In tissues with high energetic demands, oxygen is rapidly consumed, which increases the concentration of H⁺ and carbon dioxide. Through the Bohr effect, hemoglobin is induced to release more oxygen to supply cells that need it.