Oxy-haemoglobin dissociates into oxygen and deoxy-haemoglobin at

Options

A. (1) low oxygen pressure in tissues
B. (2) high oxygen pressure in tissues
C. (3) equal oxygen pressure inside and outside tissue
D. (4) all times irrespective of oxygen pressure

Answer

**Step-by-Step Solution:**

1. **Understanding Oxy-haemoglobin:** Oxy-haemoglobin is formed when oxygen binds to haemoglobin in red blood cells. This compound is crucial for transporting oxygen from the lungs to the tissues in the body.

2. **Dissociation of Oxy-haemoglobin:** The process of oxy-haemoglobin dissociating into oxygen and deoxy-haemoglobin occurs when the conditions in the tissues are right for oxygen release.

3. **Factors Influencing Dissociation:** Several factors affect the dissociation of oxy-haemoglobin:
- **Partial Pressure of Oxygen (pO2):** A low partial pressure of oxygen in the tissues promotes the release of oxygen from oxy-haemoglobin.
- **Partial Pressure of Carbon Dioxide (pCO2):** An increase in pCO2 can also facilitate the dissociation of oxygen from haemoglobin.
- **pH Levels:** A decrease in pH (increase in hydrogen ions) can promote the release of oxygen (Bohr effect).
- **Temperature:** Higher temperatures can also lead to increased dissociation of oxygen from haemoglobin.

4. **Identifying the Correct Condition:** Among the options provided:
- Low oxygen pressure inside the tissues is a condition that promotes the dissociation of oxy-haemoglobin.
- High oxygen pressure in tissues would not favor dissociation; rather, it would favor binding.
- Equal oxygen pressure inside and outside the tissue would not lead to a net movement of oxygen.
- The option stating "all times irrespective of oxygen pressure" is incorrect as the dissociation is dependent on the oxygen pressure.

5. **Conclusion:** The correct answer is that oxy-haemoglobin dissociates into oxygen and deoxy-haemoglobin at low oxygen pressure in the tissues.

**Final Answer:** Oxy-haemoglobin dissociates into oxygen and deoxy-haemoglobin at low oxygen pressure in the tissues.

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