Haldane effect is defined as: September 2010
**Core Concept**
The Haldane effect is a physiological phenomenon where the binding of oxygen to hemoglobin results in a decrease in the partial pressure of carbon dioxide in the blood. This occurs because the binding of oxygen to hemoglobin causes a conformational change that reduces the affinity of hemoglobin for carbon dioxide. As a result, carbon dioxide is released from the blood into the lungs, where it is exhaled.
**Why the Correct Answer is Right**
The Haldane effect is an important mechanism that helps to regulate the levels of carbon dioxide in the blood. When oxygen binds to hemoglobin, it causes a decrease in the affinity of hemoglobin for carbon dioxide, which allows carbon dioxide to be released from the blood into the lungs. This process is facilitated by the Bohr effect, which states that the affinity of hemoglobin for oxygen is inversely proportional to the partial pressure of carbon dioxide. As a result, when carbon dioxide levels are high, hemoglobin releases oxygen to the tissues and binds carbon dioxide, helping to regulate the acid-base balance in the body.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is not a correct definition of the Haldane effect, which specifically refers to the release of carbon dioxide from the blood into the lungs when oxygen binds to hemoglobin.
* **Option B:** This option is vague and does not accurately describe the Haldane effect.
* **Option C:** This option is incorrect because it describes the Bohr effect, which is a related but distinct phenomenon.
**Clinical Pearl / High-Yield Fact**
The Haldane effect is an important mechanism that helps to regulate the levels of carbon dioxide in the blood and is essential for maintaining acid-base balance in the body. It is also an important consideration in the management of patients with respiratory acidosis or alkalosis.
**Correct Answer:** C.