Question

The function of bicarbonate ion in the digestive tract is to
A. Neutralize stomach acid
B. Promote phagocytosis by white blood cells
C. Carry oxygen to the lungs
D. Help in the blood clotting mechanism
E. None of the above

Answer 1

Hint: After the digestion of highly acidic juice in the stomach, bicarbonate ions increases the pH of the stomach. It also controls the pH level in the small intestine.

Complete answer:
Let’s discuss the options and find out the correct answer.
A. Neutralize stomach acid: As soon as acidic chyme enters the small intestine from the stomach, a large amount of bicarbonate ions are secreted in the intestine. It dilutes the acidic content and increases the pH in order to maintain the internal pH of the intestine. Hence, option A is correct.
B. Promote phagocytosis by white blood cells: Phagocytes are a kind of white blood cells that use the process of phagocytosis in order to engulf the bacterias, dying cells and foreign compounds to protect the body. Hence, option B is incorrect.
C. Carry oxygen to the lungs: The air sac is enclosed by a large number of fine blood vessels. The oxygen containing inhaled air is passed through the thin lining of the air sac and inside the blood vessels. The oxygen is then transported around the body in order to reach every cell in the body. Hence, option C is incorrect.
D. Help in the blood clotting mechanism: Platelets are very small blood vessels that help our body to form clots preventing the loss of excessive blood. Whenever any of our blood vessels is damaged, the platelets receive signals to form clots. Hence, option D is incorrect.
Hence, option A: Neutralize stomach acid is the correct answer.

Note: After the bicarbonate ions increase the pH of the acidic chyme, activation of pancreatic digestive enzyme takes place for further digestion.