The transport of carbon dioxide as hydrogen carbonate ions

Question 1

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Answer 1

CO2 reacts with water to form carbonic acid (H2CO3), catalysed by the enzyme carbonic anhydrase

Question 2

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Answer 2

H2CO3 dissociates to H+ and HCO3-

Question 3

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Answer 3

H+ binds to haemoglobin forming haemoglobinic acid, causing haemoglobin to release oxygen.

Question 4

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Answer 4

This prevents the blood from becoming too acidic (H+ ions reduce pH)

Question 5

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Answer 5

It also causes the Bohr effect: at high pCO2, haemoglobin releases oxygen so it can diffuse into respiring tissues

Question 6

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Answer 6

HCO3- ions leave red blood cells and are transported via plasma, while chloride ions (Cl-) enter red blood cells.

Question 7

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Answer 7

This is called the chloride shift, and it maintains the charge balance by preventing excessive positive charge in red blood cells