If a person living at sea level migrates to about 8000 feet high hill, his blood after fifteen days will mainly

Options

A. (a) have fewer WBC
B. (b) have more plasma
C. (c) have an increase in volume of serum
D. (d) have a greater number of RBC and more hemoglobin

Answer

**Step-by-Step Solution:**

1. **Understanding the Scenario**: A person living at sea level migrates to a high altitude of about 8000 feet. At this altitude, the atmospheric pressure is lower, which means there is less oxygen available in the air.

2. **Initial Reaction to High Altitude**: Upon reaching high altitude, the individual may experience altitude sickness, also known as acute mountain sickness (AMS). Symptoms can include headache, nausea, and shortness of breath due to reduced oxygen availability (hypoxia).

3. **Physiological Adaptation**: To adapt to the lower oxygen levels over time (approximately 15 days), the body undergoes several physiological changes. One of the main adaptations is an increase in the production of red blood cells (RBCs) and hemoglobin, which is the protein in RBCs that carries oxygen.

4. **Effects on Blood Composition**: The increase in RBCs and hemoglobin helps to enhance the oxygen-carrying capacity of the blood, compensating for the lower oxygen availability at high altitudes. This adaptation is crucial for maintaining adequate oxygen supply to the body's tissues.

5. **Evaluating the Options**:
- Option A: Fewer WBCs - Incorrect, as WBCs are not directly involved in the adaptation to altitude.
- Option B: More plasma - Incorrect, as the body does not primarily increase plasma volume in response to altitude.
- Option C: Increase in volume of serum - Incorrect, as serum volume does not significantly change in this context.
- Option D: Greater number of RBCs and more hemoglobin - Correct, as this is the primary adaptation to counteract lower oxygen levels.

6. **Conclusion**: After 15 days at high altitude, the person's blood will mainly have a greater number of red blood cells (RBCs) and more hemoglobin.

**Final Answer**: D) Have a greater number of RBC and more hemoglobin.

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