Question

In lungs, in order to facilitate the removal of $C{O}_2$ from the blood, there is an exchange of ions between RBC and the plasma, which involves the movement of

• A. Chloride ions from RBC to plasma
• B. $C{l}^{-}$ ions from plasma to RBC
• C. Bicarbonate ions from RBC to plasma
• D. $C{l}^{-}$ and bicarbonate ions as in (a) and (b)

Answer 1

Answer: (B)

$C{l}^{-}$ ions from plasma to RBC

In the lungs, in order to facilitate the removal of CO${}_2$ from the blood, there is an exchange of ions between RBC and the plasma by a process known as chloride shift or the Hamburger shift.

Carbondioxide released from the tissue cells passes the interstitial fluid and reaches the plasma and finally enters RBC. It combines with water and form carbonic acid in the presence of enzyme carbonic anhydrase. The carbonic acid dissociates to form bicarbonate ions which is exchanged with chloride ions in the plasma.

So, the correct answer is option B.