Question

The most important buffer in the blood consists of:

• A. $HCl$ and ${Cl}^{-}$
• B. $H_2{CO}_3$ and $H{CO}_3^{-}$
• C. $H_2{CO}_3$ and ${Cl}^{-}$
• D. $HCl$ and $H{CO}_3^{-}$

Answer 1

Answer: (B)

$H_2{CO}_3$ and $H{CO}_3^{-}$

The buffer system present in blood is $H_{2}C{O}_3$ and $NaHC{O}_3.$ There exists a balance between this buffer system and $C{O}_2.$

This buffer system is maintained so that if there is any addition of acid or base into bloodstream, the buffer system will resist the change and maintain constant $pH$ as it contain weak acid $H_{2}C{O}_3$ and its conjugate base $NaHC{O}_3$.