Final answer:
Hypoxemia stimulates the kidneys to produce erythropoietin (EPO), which leads to an increased production of erythrocytes, helping the body to maintain oxygen levels in the blood.
Step-by-step explanation:
Hypoxemia, resulting from conditions such as hemorrhage, high altitude, or emphysema, may stimulate the kidneys to produce the hormone erythropoietin (EPO). This hormone then stimulates the production of erythrocytes (red blood cells), increasing their number in circulation. With more erythrocytes available, there is more hemoglobin to transport oxygen, helping to maintain oxygen levels in the blood despite the low saturation of each hemoglobin molecule. Acclimatization occurs over time, allowing individuals to partake in physical exertion without developing acute mountain sickness (AMS), as their body adjusts to the lower oxygen availability by increasing erythrocyte production via EPO.