Biology – Transport of oxygen and carbon dioxide | e-Consult

The Bohr effect describes the relationship between blood pH and the affinity of haemoglobin for oxygen and carbon dioxide. It states that a decrease in blood pH (i.e., an increase in hydrogen ion concentration) reduces haemoglobin's affinity for oxygen and increases its affinity for carbon dioxide.

This effect is crucial for efficient CO2 transport because in metabolically active tissues, CO2 is produced, leading to an increase in hydrogen ion concentration. The increased hydrogen ion concentration then reduces haemoglobin's ability to bind oxygen, causing haemoglobin to release oxygen and bind more CO2. This facilitates the removal of CO2 from the tissues and its transport to the lungs.

The Bohr effect is mediated by several factors:

• Hydrogen ion concentration: Increased H+ concentration reduces haemoglobin's oxygen affinity.
• CO2 concentration: Increased CO2 concentration promotes the formation of carbaminohemoglobin.
• Temperature: Increased temperature promotes the release of oxygen and the binding of CO2.
• 2,3-Bisphosphoglycerate (2,3-BPG): Increased levels of 2,3-BPG reduce haemoglobin's oxygen affinity, promoting oxygen release and CO2 binding. 2,3-BPG is produced in red blood cells in response to low oxygen levels.

In summary, the Bohr effect ensures that CO2 is efficiently transported from the tissues to the lungs when metabolic activity is high, allowing for the removal of waste CO2 and maintaining proper blood pH.