Question

Which of the following statements are true/false.
a. The blood transports $CO_2$ comparatively easily because of its high solubility.
b. Approximately 8-9% of $CO_2$ is transported being dissolved in the plasma of blood
c. The carbon dioxide produced by the tissues, diffuses passively into the blood stream and passes into red blood corpuscles and react with water to form $H_2CO_3$ .
d. The oxyhaemoglobin ($HbO_2$ ) of the erythrocytes is basic.
e. The chloride ions diffuse from plasma into the erythrocytes to maintain ionic balance.

• A. a, c and e are true, b and d are false.
• B. a, c and e are false, b and d are true.
• C. a, b and d are true, c and e are false.
• D. a, b and d are false, c and e are tme.
• E. a, b and c are true, d and e are false.

Answer 1

Answer: (A)

$CO_{2}$ transport in blood : Transport of $CO_{2}$ by blood is much easier/simple than that of $O_{2}$ due to high solubility of $CO_{2}$ in water.
Most of the $ \, CO_{2}, \, i.e.,$ 70% of $CO_{2}$ is transported as bicarbonate $\left(\right.HCO_{3}^{-}\left.\right)$ in blood. 23% as carbaminohaemoglobin $\left(\right.HbCO_{2}\left.\right)$ and 7% of $CO_{2}$ is dissolved in the plasma.
$CO_{2}$ produced by the tissues, diffuses passively into the blood plasma and reacts with water forming carbonic acid. The reaction occurs very rapidly inside RBCs because of the presence of enzyme carbonic anhydrase.
Chloride shift : To maintain electro-chemical neutrality of plasma many chloride ions diffuse from plasma into RBCs and bicarbonates pass out. The chloride content of RBCs increases when oxygenated blood becomes deoxygenated. This is termed as chloride shift or Hamburger shift.
Haldane's effect : Oxygenated blood behaves as strong acid. More and more oxyhaemoglobin is formed in lungs, which releases $H^{+} \, , \, i.e.,$ increasing the acidity of blood. This $H^{+}$ combines with bicarbonate forming carbonic acid and soon dissociates.