Question

Which of the following point on the oxygen dissociation curve represent p50 of HbO₂ in the graph given below?

• A. $A$
• B. $B$
• C. $C$
• D. $D$

Answer 1

Answer: (A)

p50 represents the partial pressure of a gas required to achieve $50\%$ saturation of a particular protein's binding sites. The oxygen dissociation curve plots the $\%$ saturation against the partial pressure of oxygen, and its contribution to the total oxygen content. This is an S-shaped curve due to the alterations in hemoglobin's affinity for oxygen in response to other physiologic factors. Please note the dotted line at the bottom of the graph. This represents the dissolved $O_2$ . Dissolved $O_2$ is a linear relationship to its partial pressure and results in a straight line.