Breathing and Exchange of Gases Question 31
31. Although much $CO_2$ is carried in blood, yet blood does not become acidic, because [1995]
(a) it is absorbed by the leucocytes
(b) blood buffers play an important role in $CO_2$ transport.
(c) it combines with water to form $H_2 CO_3$ which is neutralized by $NaCO_3$
(d) it is continuously diffused through tissues and is not allowed to accumulate
Show Answer
Answer : b
Hints & Solution
(b) $CO_2$ enters $RBC$ and reacts with water to form carbonic acid. Carbonic acid dissociates to form bicarbonate and hydrogen ions. Some bicarbonate ions are transported in erythrocytes while some diffuse into the blood plasma. Exit of bicarbonate ions change the ionic balance between the plasma and erythrocytes. To restore this balance chloride ions diffuse from plasma into erythrocytes. Due to this the $pH$ of blood is maintained.
