Question

Under a given concentration in blood, dissociation of oxyhaemoglobin will increase if

• A. pH of blood falls.
• B. pH of blood rises.
• C. $C{O}_2$ concentration in blood falls.
• D. Free fatty acid concentration in blood falls.

Answer 1

The correct option is A pH of blood falls.

At $P{O}_2$ of 100 mm Hg, haemoglobin is nearly 100% saturated with oxygen, and at 40 mm Hg, haemoglobin is 75% saturated. The oxyhaemoglobin dissociation curve describes the relationship between oxygen saturation of blood and $P{O}_2$. Exposure of blood to the high $P{O}_2$ in the respiratory zone of the lung results in binding of a substantial amount of oxygen. When pH falls in a tissue, means the amount of $C{O}_2$ is also increased and the need for oxygen is increased. So, at a lower pH haemoglobin releases oxygen faster.