Question

In human body ‐‐‐‐‐ system operates to maintain pH of blood plasma. 

• A. The acetate buffer
• B. The lysis buffer
• C. The potassium citrate
• D. The carbonic acid

Answer 1

The Correct Option is D

The question asks about the system in the human body that operates to maintain the pH of blood plasma. The correct answer is "The carbonic acid."

Let's analyze why the carbonic acid (H₂CO₃) is the correct answer:

1. Role of Carbonic Acid in Blood pH Regulation: The carbonic acid-bicarbonate buffer system is crucial for maintaining the pH balance of blood plasma. It works as follows:
   • Carbonic acid (H₂CO₃) dissociates into bicarbonate (HCO₃^-) and a hydrogen ion (H⁺): \text{H}_2\text{CO}_3 \rightleftharpoons \text{HCO}_3^{-} + \text{H}^+ .
   • This reversible reaction allows the buffer to neutralize excess acids or bases in the blood effectively, helping to maintain a stable pH level around 7.4.
2. Why Other Options are Incorrect:
   • The acetate buffer: This is used mainly in laboratory settings and is not naturally used by the human body for blood pH regulation.
   • The lysis buffer: This is used to break open cells and is not related to pH regulation in the bloodstream.
   • The potassium citrate: It can contribute to alkalizing the urine but is not a primary buffer system in the blood.

The carbonic acid-bicarbonate buffer system is essential for homeostasis, as it helps resist pH changes in blood, thereby ensuring proper physiological functions. Thus, the correct choice is carbonic acid.