Alan Forsythe, a middle-aged college professor from Boston, is in the Swiss Alps studying astronomy during his sabbatical leave. He has been there for two days and plans to stay the entire year. However, he notices that he is short of breath when he walks up steps and tires easily with any physical activity. His symptoms gradually disappear, and he feels fine after less than a month. Upon returning to the United States, he has a complete physical exam and is told that his erythrocyte count is higher than normal. a. Attempt to explain this finding. b. Will his RBC count remain at this higher-than-normal level? Why or why not?

Verified step by step guidance

1. Step 1: Understand the context of the problem. Alan Forsythe is experiencing shortness of breath and fatigue in the Swiss Alps, which is a high-altitude environment.
2. Step 2: Recognize that at high altitudes, the air pressure is lower, leading to reduced oxygen availability. This condition is known as hypoxia.
3. Step 3: Explain the body's physiological response to hypoxia. The body compensates for lower oxygen levels by producing more erythrocytes (red blood cells) to increase oxygen transport capacity.
4. Step 4: Address part a. Alan's higher erythrocyte count is a result of his body's adaptation to the high-altitude environment, where more red blood cells are needed to carry sufficient oxygen.
5. Step 5: Address part b. Upon returning to lower altitudes, Alan's RBC count will likely decrease over time as his body no longer needs the extra erythrocytes to compensate for reduced oxygen availability.

Key Concepts

Erythropoiesis

Erythropoiesis is the process of producing red blood cells (RBCs) in the bone marrow. It is stimulated by erythropoietin, a hormone released by the kidneys in response to low oxygen levels in the blood. In high-altitude environments, like the Swiss Alps, the lower oxygen availability can trigger increased erythropoiesis, leading to a higher RBC count to enhance oxygen transport in the body.

Acclimatization

Acclimatization refers to the physiological adjustments that occur in response to changes in the environment, such as altitude. When individuals move to higher altitudes, their bodies adapt by increasing RBC production and improving oxygen utilization. This process can take several weeks, which explains why Alan's symptoms improved after a month as his body adjusted to the altitude.

Homeostasis

Homeostasis is the body's ability to maintain stable internal conditions despite external changes. After returning to lower altitudes, Alan's body will likely revert to its normal RBC count as oxygen levels stabilize. This is because the stimulus for increased erythropoiesis (low oxygen) is removed, and the body seeks to maintain balance, reducing the excess RBCs produced during his time in the Swiss Alps.