Question

Which of the following factors affect the oxygen dissociation curve?
A. Partial pressure of carbon dioxide
B. pH ($H^+$ ion concentration)
C. Temperature
D. Partial pressure of oxygen
E. All of the above

Answer 1

Hint: Oxygen dissociation curves show the relationship between oxygen levels (as partial pressure) and hemoglobin saturation.

Complete Answer:
- The oxygen dissociation curve is a graph with oxygen partial pressure along the horizontal axis and oxygen saturation on the vertical axis, which shows an S-shaped relationship. The oxygen dissociation curve is affected by several important factors that affect the affinity of hemoglobin to oxygen thereby affecting the oxygen-hemoglobin dissociation curve. These factors include the (1) pH (2) temperature (3) carbon dioxide (4) 2, 3-BPG and (5) carbon monoxide.
- When the hydrogen ion concentration ( pH), the temperature, the carbon dioxide concentration, or the amount of 2,3-BPG present in the red blood cell is increased, ultimately the affinity of hemoglobin to oxygen decreases. Therefore shift the curve to the right side. This allows us to unload more oxygen to our tissues.
- On the other hand, when the concentration of carbon monoxide is increased, the affinity of hemoglobin for oxygen is increased. Therefore shift the curve to the left side. This means that less oxygen will actually be delivered to our tissues.

Therefore, option E is correct.

Note: It is to be noted that the hemoglobin of the fetus has a slightly different molecular composition to adult hemoglobin. Therefore, it has a higher affinity for oxygen (the dissociation curve is shifted to the left).