Question

The pH of blood is maintained by a buffering system, consisting predominately by hydrogen carbonate ions, HCO₃^-, in equilibrium with carbonic acid, H₂CO₃, which decomposes completely to CO₂ and H₂O.

H₃O⁺ + HCO₃^- ⇌ 2H₂O + CO₂

Questions

1. During exercise, CO₂ is produced at a rapid rate in muscle.

How does exercising affect the pH of blood? Give a reason for your answer.

2. Hyperventilation (rapid and deep breathing) can occur during intense exercise.

How does hyperventilation affect the pH of the blood? Give a reason for your answer.

3. The normal first aid treatment for hyperventilation is to have the patient breathe in and out of a paper bag.

Explain briefly why this treatment works and what effect the paper bag treatment has on the pH of the blood.

Answer 1

1) WHen we are engaged in physical exercise, the muscles of the body use up oxygen. This is because the body converts chemical energy in glucose to mechanical energy during which the tissues need oxygen. The oxygen comes from hemoglobin in the blood.

CO₂ and H⁺ are produced when the glucose in the body is broken down and are removed from the muscle via the blood. The production and removal of CO₂ and H⁺, together with the use and transport of O₂ results in the decrease in the pH of the blood.

2) Hyperventilation is the abnormal increase in breathing during which the rate of removal of carbon dioxide from the blood increases. this causes the H+ concrentration to decrease and causes the pH of blood to increase and become more alkaline. When the pH of the blood is more alkaline, hemoglobin binds more tightly with oxygen.

3) When during hyperventilation, a significant amount of CO2, the blood pH increases as carbon dioxide is being removed. The idea behind breathing into a paper bag is that rebreathing exhaled air helps the body to put CO2 back into the blood. This helps in restoring the pH of the blood to the normal level.