Which of the following is NOT a chemical buffer system? a– phosphate bc– bicarbonate c– protein d- nitrogen
The Correct Answer and Explanation is:
The correct answer is d – nitrogen.
Explanation:
A buffer system is crucial in maintaining a stable pH within the body’s fluids, ensuring that processes like enzyme activity, cellular respiration, and muscle contractions occur optimally. Buffer systems resist changes in pH when small amounts of acids or bases are added to body fluids. The primary buffer systems in the human body include the phosphate buffer system, the bicarbonate buffer system, and the protein buffer system.
- Phosphate Buffer System:
The phosphate buffer system plays a significant role in buffering the intracellular fluid (inside cells) and, to a lesser extent, extracellular fluid (outside cells). It consists of dihydrogen phosphate ions (H₂PO₄⁻) and hydrogen phosphate ions (HPO₄²⁻). When there is an excess of hydrogen ions (H⁺), the hydrogen phosphate ion acts as a weak base and accepts H⁺, forming dihydrogen phosphate. This process helps to prevent an excessive decrease in pH, particularly in the kidney’s tubular fluids. - Bicarbonate Buffer System:
The bicarbonate buffer system is the most significant buffer system in the extracellular fluid, including blood plasma. It consists of bicarbonate ions (HCO₃⁻) and carbonic acid (H₂CO₃). When the pH drops (becoming more acidic), bicarbonate ions neutralize excess hydrogen ions to form carbonic acid. Conversely, when pH rises (becoming more basic), carbonic acid dissociates, releasing hydrogen ions and helping restore pH balance. - Protein Buffer System:
Proteins, due to their abundance and structure, serve as important buffers, especially within cells and the blood. Proteins contain amino acids with functional groups that can release or bind hydrogen ions as needed. For instance, hemoglobin in red blood cells binds hydrogen ions, buffering the blood’s pH as carbon dioxide levels fluctuate. - Nitrogen:
Nitrogen is not a component of any buffer system in the human body. While nitrogen is a major component of amino acids and proteins, it does not participate in buffering. Nitrogen gas (N₂) is inert and does not engage in chemical reactions that would alter pH levels.
In conclusion, nitrogen is not a chemical buffer system, while phosphate, bicarbonate, and protein are essential buffer systems maintaining pH balance in the body.