Question

which of the following are used as buffers for acid-base balance in the body fluids? (select all that apply)
check all that apply
□ protein
□ carbonic acid
□ bicarbonate ions
□ calcium

Explanation:

• Protein: Proteins can act as buffers as they contain amino acid residues with ionizable groups (e.g., carboxyl and amino groups) that can accept or donate protons to help maintain pH.
• Carbonic acid: The carbonic acid - bicarbonate buffer system ($\ce{H2CO3/HCO3^-}$) is a key buffer in body fluids. Carbonic acid ($\ce{H2CO3}$) can dissociate to release $\ce{H+}$ or combine with $\ce{H+}$ to help regulate pH.
• Bicarbonate ions: As part of the carbonic acid - bicarbonate buffer system, bicarbonate ions ($\ce{HCO3^-}$) can accept $\ce{H+}$ (acting as a base) to form carbonic acid, helping to buffer excess acid.
• Calcium: Calcium is not a buffer for acid - base balance. Its main roles are in bone health, muscle contraction, nerve function, etc., and it does not participate in proton - accepting or - donating reactions for pH regulation.

Answer:

A. Protein, B. Carbonic acid, C. Bicarbonate ions