Question

A decrease in the pH of human blood would

• A. Decrease breathing rate
• B. Increase heart rate
• C. Decrease the amount of O${}_2$ unloaded from haemoglobin
• D. Decrease cardiac output

Answer 1

Answer: (C)

Decrease the amount of O${}_2$ unloaded from haemoglobin

Blood is slightly basic, alkaline with a pH range of 7.35 to 7.45. The decrease in this pH of human blood results in a decrease in the amount of oxygen unloaded from haemoglobin. Each haemoglobin molecule has the capacity to carry four oxygen molecules. The amount of oxygen binding to the haemoglobin is related to the partial pressure of oxygen to which the haemoglobin is exposed. Increased carbon dioxide and decreased pH decreases the capacity of haemoglobin to carry oxygen. When the partial pressure will be low, the amount of carbon dioxide will be high. As a result of which oxygen is taken up by lungs and efficient unloading of oxygen in tissues will take place.

So, the correct answer is option C.