In which part of the body is the Haldane effect primarily observed?

• A. Heart
• B. Kidneys
• C. Lungs
• D. Systemic tissues

Answer: (C)

The Haldane effect is primarily observed in the lungs. This physiological phenomenon describes how deoxygenation of the blood increases its ability to carry carbon dioxide. In the lungs, where oxygen levels are high, hemoglobin binds to oxygen, which in turn facilitates the release of carbon dioxide from the hemoglobin into the alveoli to be exhaled.

As deoxygenated blood enters the lungs, the lower partial pressure of oxygen promotes the release of carbon dioxide from hemoglobin, which can then be expelled from the body. This mechanism is integral to efficient gas exchange, ensuring that as oxygen is taken up, carbon dioxide— a waste product of cellular metabolism—is released. Thus, understanding this effect highlights the importance of the lungs in maintaining proper gas exchange and overall respiratory function.