Question

In mammals, carbon dioxide is transported from tissues to respiratory surface by

• A. Plasma and RBCs
• B. Plasma only
• C. RBCs and WBCs
• D. Red blood corpuscles only

Answer 1

The correct option is A Plasma and RBCs

Transport of $C{O}_2$

• Carbon dioxide is transported by the blood in three forms:
• Dissolved state - 5 to 7% of carbon dioxide is transported through the plasma of blood in the dissolved state.
• Bicarbonates - 70% of the carbon dioxide is transported in the form of bicarbonates. The $C{O}_2$ from the tissues enters the RBCs and combines with water to form carbonic acid $\left(H_{2}C{O}_3\right)$. Carbonic acid then dissociates into $H^{+}$ and bicarbonate ions $\left(HC{O}_3^{-}\right)$.
• Carbamino haemoglobin - 23% of carbon dioxide is transported as carbamino-haemoglobin. Carbon dioxide combines with amino groups of haemoglobin to form carbamino-haemoglobin.

Final answer: (3) Plasma and RBCs