Consider the oxygen dissociation curve for human haemoglobin on the right

The "S" shape of the curve is indicative of haemoglobin's low solubility in water; high solubility in water; high solubility in oxygen; high affinity for oxygen.

According to the graph, what will happen if the oxygen level drops due to tissue utilisation? haemoglobin is destroyed. Haemoglobin responds by mopping up carbon dioxide. Haemoglobin responds by releasing more oxygen. Haemoglobin responds by trapping more oxygen.

According to the graph, what will happen if the oxygen level increases in the tissues as happens when blood enters the lungs? haemoglobin is destroyed. Haemoglobin responds by mopping up carbon dioxide. Haemoglobin responds by releasing more oxygen. Haemoglobin responds by trapping more oxygen.

The range of oxygen pressure in the tissues ranges from say 2 to 6 kPa. Which comment is true according to the graph on the right? Haemoglobin allows the blood to become saturated at high oxygen pressures above 30 kPa. A small reduction in oxygen pressure results in a large amount of oxygen being given out by haemoglobin. A small reduction in oxygen pressure results in a small amount of oxygen being given out by haemoglobin.

The graph on the right shows the "S" shaped oxygen dissociation curve for haemoglobin. What would the difference be if the relationship between percentage saturation and oxygen pressure was a linear one as shown by the blue line? To help you answer this question consider the:

- percentage saturation at 6 kPa of both graphs;

- the change in percentage saturation of both graphs as the pressure of oxygen changes from 4 to 2 kPa.

The oxygen dissociation graphs on the right are taken at three different concentrations of carbon dioxide. As you can see, as the concentration CO₂ increases the graph shifts down and to the right.

A shift to the right means that haemoglobin needs a higher pressure of oxygen to saturate the blood; haemoglobin needs a lower pressure of oxygen to saturate the blood; less haemoglobin is needed to saturate the blood.

Consider the graph on the right. Which comment is true? carbon dioxide makes haemoglobin better at absorbing oxygen; carbon dioxide allows oxygen to bind more strongly to haemoglobin. carbon dioxide makes haemoglobin less efficient at absorbing carbon dioxide; carbon dioxide makes haemoglobin less efficient at releasing oxygen.

It is argued that the influence of carbon dioxide on haemoglobin is a beneficial one? Discuss .
Consider the level of carbon dioxide in the respiring tissue and the level of carbon dioxide in the lungs. You would assume that the carbon dioxide level in the lungs is lower due to its continual escape into the atmosphere.

Solution