External respiration allows the exchange of carbon dioxide for oxygen at any altitude which of the following is not an adaptation to living high above the sea level ?

Options

A. an increase in 2,3 bpg concentration which shifts the `O_(2)` dissociation curve to the right
B. increased production of red blood cells by the bone marrow
C. decreased synthesis of erythropoetin by the kidney
D. hyperventilation

Answer

To solve the question regarding adaptations to living at high altitudes, we need to analyze each option provided in the context of how the body responds to lower oxygen levels at high altitudes.

### Step-by-Step Solution:

1. **Understand External Respiration**: External respiration is the process of exchanging gases (oxygen and carbon dioxide) between the atmosphere and the blood. At high altitudes, the availability of oxygen decreases, which necessitates certain adaptations in the body to maintain oxygen supply.

2. **Evaluate the First Option - Increase in 2-3 BPG Concentration**:
- 2,3-Bisphosphoglycerate (2,3-BPG) is a compound that helps hemoglobin release oxygen more readily to tissues.
- At high altitudes, the concentration of 2,3-BPG increases, facilitating better oxygen delivery despite lower atmospheric oxygen levels.
- **Conclusion**: This is an adaptation to high altitude.

3. **Evaluate the Second Option - Increased Production of RBC by the Bone Marrow**:
- Red blood cells (RBCs) are responsible for carrying oxygen in the blood.
- At high altitudes, the body compensates for lower oxygen availability by producing more RBCs, which increases the oxygen-carrying capacity of the blood.
- **Conclusion**: This is also an adaptation to high altitude.

4. **Evaluate the Third Option - Decreased Synthesis of Erythropoietin by the Kidney**:
- Erythropoietin (EPO) is a hormone produced by the kidneys that stimulates the production of RBCs in the bone marrow.
- At high altitudes, the body needs more RBCs to cope with reduced oxygen levels, which means there should be an **increase** in erythropoietin production, not a decrease.
- **Conclusion**: This is **not** an adaptation to high altitude.

5. **Evaluate the Fourth Option - Hyperventilation**:
- Hyperventilation is an increase in breathing rate that occurs in response to lower oxygen levels.
- This physiological response helps to increase oxygen intake and is a common adaptation to high altitudes.
- **Conclusion**: This is an adaptation to high altitude.

### Final Answer:
The option that is **not** an adaptation to living high above sea level is: **Decreased synthesis of erythropoietin by the kidney**.

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