Question

Fred loves La Paz, Bolivia so much that he decides to stay there for a couple years. All of the following changes could be considered a compensatory mechanism in response to the chronically decreased oxygen content EXCEPT

a. an increase in amount of circulating red blood cells.
b. an increase in oxygen extraction by perfused cells.
c. an increase in hemoglobin’s affinity for oxygen.
d. a decrease in heart rate.

Answer 1

d. a decrease in heart rate.

Step-by-step explanation:

As the altitude rises, the number of oxygen molecules in the air decreases. Lower oxygen levels at high altitudes stimulate the release of erythropoietin (EPO), which is associated with the increased red blood cells, i.e., it enables more oxygen molecules to be transported to cells and tissues. Moreover, at high latitudes, the increased hemoglobin (Hb)–oxygen affinity helps to safeguard arterial O2 saturation and thus mitigates the effects of low oxygen concentration in arterial blood (arterial hypoxemia). Finally, oxygen extraction depends on an appropriate supply of oxygen in the blood vessels. An increased oxygen extraction occurs when there is an inadequate circulating blood volume or when the number of red blood cells decreases below the normal levels.