There is increase in number of RBCs at higher altitudes to compensate for

Options

A. High rate of destruction
B. Lower turn-over
C. Low level of oxygen
D. Higher requirement of energy.

Answer

**Step-by-Step Solution:**

1. **Understanding the Environment at Higher Altitudes:**
- At higher altitudes, the atmospheric pressure is lower compared to sea level. This leads to a decrease in the availability of oxygen in the air.

2. **Recognizing the Impact of Low Oxygen Levels:**
- The decrease in atmospheric pressure results in lower oxygen levels (hypoxia) in the environment, which means that the body receives less oxygen than it needs for its metabolic processes.

3. **Hormonal Response to Low Oxygen:**
- In response to low oxygen levels, the kidneys detect this deficiency and release a hormone called erythropoietin (EPO).

4. **Role of Erythropoietin:**
- Erythropoietin acts on the bone marrow, stimulating it to increase the production of red blood cells (RBCs).

5. **Compensation for Oxygen Demand:**
- The increase in the number of RBCs enhances the blood's capacity to carry oxygen, compensating for the lower oxygen availability at high altitudes. This adaptation helps ensure that vital organs and muscles receive adequate oxygen for their functions.

6. **Conclusion:**
- Therefore, the increase in the number of RBCs at higher altitudes is primarily to compensate for the low level of oxygen available in the environment.

**Final Answer:**
The increase in the number of RBCs at higher altitudes is to compensate for the low level of oxygen.

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