Class 11 NEET Biology Breathing and Exchange of Gases

(c) : About 70% of CO2 released diffuses into the plasma and then into the RBCs. Here, it combines with water to form carbonic acid. Carbonic acid dissociates into bicarbonate and hydrogen ions. Hydrogen ions are picked up by proteins and a small amount of bicarbonate ions is transported in the RBCs, whereas most of them diffuse into the plasma to be carried by it. About 7% of CO2 is transported as dissolved in plasma and 23% of CO2 combines with Hb to form carbaminohaemoglobin.

CO2+H2O

carbonic

⇌

anhydrase

H2CO3

carbonic‌acid

H2CO3⇌H++

HCO3−

bicarbonate‌ion