What factors promote oxygen binding to and dissociation from hemoglobin?
The correct answer and explanation is :
Factors Promoting Oxygen Binding and Dissociation from Hemoglobin
The binding and release of oxygen (O₂) to hemoglobin (Hb) are influenced by several factors:
Factors Promoting Oxygen Binding (Affinity Increases)
- High Partial Pressure of Oxygen (pO₂) – In the lungs, where pO₂ is high (~100 mmHg), oxygen readily binds to hemoglobin.
- Increased pH (Bohr Effect) – A more alkaline environment (higher pH) enhances hemoglobin’s oxygen affinity.
- Low Temperature – Cooler temperatures stabilize the oxygen-bound form of hemoglobin.
- Low Carbon Dioxide (CO₂) Levels – Reduced CO₂ in the lungs shifts hemoglobin to a high-affinity state.
- Low 2,3-Bisphosphoglycerate (2,3-BPG) – Lower levels of 2,3-BPG in red blood cells increase oxygen binding.
Factors Promoting Oxygen Dissociation (Affinity Decreases)
- Low Partial Pressure of Oxygen (pO₂) – In tissues where pO₂ is lower (~40 mmHg or less), hemoglobin releases oxygen.
- Decreased pH (Bohr Effect) – Higher acidity (low pH), caused by lactic acid or CO₂ accumulation, reduces oxygen affinity.
- Higher Temperature – Active tissues generate heat, reducing hemoglobin’s oxygen affinity.
- High Carbon Dioxide (CO₂) Levels – CO₂ binds to hemoglobin, facilitating oxygen release (Haldane effect).
- High 2,3-BPG Levels – This molecule binds to hemoglobin, stabilizing the deoxygenated state, promoting oxygen release.
Explanation
Hemoglobin is a protein in red blood cells that transports oxygen from the lungs to tissues. It exhibits cooperative binding, meaning that when one O₂ molecule binds, the affinity for additional O₂ molecules increases. The Bohr effect describes how pH influences hemoglobin’s oxygen affinity—lower pH (acidic) promotes oxygen unloading, while higher pH (alkaline) enhances binding. The Haldane effect describes how oxygenation of hemoglobin promotes CO₂ release, whereas deoxygenated hemoglobin favors CO₂ binding. These physiological adjustments ensure efficient oxygen delivery and CO₂ removal.
