Question

The oxygen affinity of hemoglobin _____ as pH decreases from the value of 7.4 found in the lungs, at 100 torr of oxygen partial pressure, to pH 7.2 and an oxygen partial pressure of 20 torr found at active muscle.

MCQ Options:
a. Increases
b. Decreases
c. Remains constant
d. Fluctuates

Answer 1

The affinity of hemoglobin for oxygen decreases as blood pH decreases and the oxygen dissociation curve shifts to the right, indicating reduced oxygen affinity at the active muscle site.

Step-by-step explanation:

The oxygen affinity of hemoglobin decreases as pH decreases from the value of 7.4 found in the lungs, to pH 7.2 and an oxygen partial pressure of 20 torr found at active muscle. When carbon dioxide levels in the blood rise, it reacts with water forming bicarbonate (HCO3) and hydrogen ions (H+). The increase in H+ lowers the blood's pH. This reduction in pH, as well as an increase in temperature from active muscles, shifts the oxygen dissociation curve to the right, which means hemoglobin will have a lower affinity for oxygen during these conditions.