Question

When under certain conditions, $P_{50}$ value in blood rises, the affinity of respiratory pigment of combining with $O_2$ will:

• A. Remain same
• B. Rise
• C. Fall
• D. First rise and then fall

Answer 1

The correct option is C Fall

The $P_{50}$ is the oxygen partial pressure at which hemoglobin is 50% saturated. The normal $P_{50}$ is 26.7 mm Hg. Shifting the oxyhemoglobin dissociation curve to the right increases $P_{50}$ and lowers the hemoglobin’s affinity for oxygen.

So the correct answer is option 'C'.