Question

Both in cells and extracellular fluids diabasic phosphate (HPO₄) and monobasic phosphate $\left(H_{2}P{O}_4^{-}\right)$ act as acid-base buffers to maintain

• A. K⁺ concentration of extracellular fluid
• B. Na⁺ concentration of extracellular fluid
• C. Na⁺ concentration of cellular fluid
• D. H⁺ concentration of cellular fluid

Answer 1

Answer: (D)

The three major buffer systems of our body are the carbonic acid bicarbonate buffer system, phosphate buffer system, and protein buffer system.
The carbonic acid-bicarbonate buffer system plays an extremely important role in maintaining the pH homeostasis of the blood.
Carbonic acid-bicarbonate buffer system converts strong bases to a weak base (bicarbonate ion), and strong acids to a weak acid (carbonic acid)
The phosphate buffer consists of phosphoric acid (H₃PO₄) in equilibrium with dihydrogen phosphate ion (H₂PO₄^–) and H⁺. The pK for the phosphate buffer is 6.8, which allows this buffer to function within its optimal buffering range at physiological pH. It plays a very minute role in the blood.
Phosphate Buffer System has 2 main components:
• Sodium salts of dihydrogen phosphate (H2PO₄¯), a weak acid.
• Monohydrogen phosphate (HPO₄^2¯), a weak base.
This system is an effective acid-base buffer to maintain the H+ concentration of cellular fluid.
Protein buffer helps to maintain acidity in and around the cells. Proteins containing amino acid histidine are also good at buffering.