Basic function of hemoglobin is –
**Core Concept**
Hemoglobin is a crucial protein in red blood cells responsible for transporting oxygen from the lungs to peripheral tissues and carbon dioxide from tissues to the lungs. It plays a vital role in maintaining the body's oxygen supply and facilitating the exchange of gases in the blood.
**Why the Correct Answer is Right**
The primary function of hemoglobin is to bind oxygen reversibly with high affinity. This is achieved through the interaction of oxygen with the heme groups in hemoglobin, which consists of four polypeptide chains (alpha and beta chains) and four heme groups. The binding of oxygen to hemoglobin is facilitated by the allosteric effect of 2,3-bisphosphoglycerate (2,3-BPG), which decreases the affinity of hemoglobin for oxygen and promotes its release in tissues. This process is essential for maintaining the optimal oxygen delivery to tissues.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the primary function of hemoglobin.
**Option B:** This option is incorrect because while hemoglobin does play a role in buffering hydrogen ions, this is not its primary function.
**Option C:** This option is incorrect because hemoglobin does not primarily function to transport carbon dioxide from tissues to the lungs; that is the role of the bicarbonate buffering system.
**Clinical Pearl / High-Yield Fact**
A key clinical correlation to remember is that conditions affecting hemoglobin, such as anemia or polycythemia, can significantly impact oxygen delivery to tissues and lead to various clinical manifestations, including fatigue, shortness of breath, and decreased exercise tolerance.
**Correct Answer: D. Transporting oxygen from the lungs to peripheral tissues and carbon dioxide from tissues to the lungs.**