Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

17. The Blood

Erythrocytes: Hemoglobin

Anatomy & Physiology

17. The Blood

Erythrocytes: Hemoglobin

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2:38 minutes

Problem 21

Textbook Question

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

Step 1: Understand the physiological response to high altitude. At high altitudes, the oxygen levels in the air are lower, leading to a condition called hypoxia (low oxygen availability). The body compensates for this by producing more erythrocytes (red blood cells) to increase the oxygen-carrying capacity of the blood.

Step 2: Explain the role of erythropoietin (EPO). The kidneys detect the reduced oxygen levels in the blood and release a hormone called erythropoietin. Erythropoietin stimulates the bone marrow to produce more erythrocytes, which explains why Alan's RBC count increased during his stay in the Swiss Alps.

Step 3: Address the gradual disappearance of symptoms. Over time, as the body adapts to the high altitude by increasing erythrocyte production, Alan's oxygen-carrying capacity improves, and his symptoms of shortness of breath and fatigue subside.

Step 4: Discuss the return to normal RBC levels. Upon returning to the United States, where oxygen levels are higher, the stimulus for increased erythropoietin production diminishes. As a result, the production of erythrocytes decreases, and the RBC count gradually returns to normal levels over time.

Step 5: Summarize the temporary nature of the adaptation. The increase in RBC count is a temporary physiological adaptation to high altitude. Once Alan is back at sea level, his body no longer needs the higher RBC count, and homeostatic mechanisms restore it to normal levels.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Erythrocyte Count

Erythrocyte count refers to the number of red blood cells (RBCs) in a given volume of blood. RBCs are crucial for transporting oxygen from the lungs to the body's tissues and returning carbon dioxide for exhalation. A higher-than-normal erythrocyte count, or erythrocytosis, can occur in response to various factors, including altitude, where lower oxygen levels stimulate increased RBC production to enhance oxygen delivery.

Physiological Adaptation to Altitude

When individuals ascend to high altitudes, such as the Swiss Alps, the body experiences lower oxygen availability. In response, it undergoes physiological adaptations, including increased erythropoietin production, which stimulates the bone marrow to produce more RBCs. This adaptation helps improve oxygen transport and utilization, allowing individuals to function better in hypoxic conditions, but may take weeks to fully develop.

Return to Sea Level

Upon returning to sea level, the body no longer requires the same level of RBC production due to the increased availability of oxygen. Consequently, the elevated erythrocyte count is likely to decrease as the body readjusts to normal oxygen levels. This process can take several weeks, as the body regulates RBC production based on oxygen needs, leading to a potential return to baseline erythrocyte levels.

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