Hemoglobin Reactions

Hemoglobin is a complex molecule, consisting of the globular protein globin and a central atom of iron held in a heterocyclic organic ring (a heme group). Hemoglobin gives red blood cells their characteristic color, and more importantly, transfers oxygen from the lungs to the body tissues.

Oxygen

The oxygenation of blood entails a reversible or equilibrium reaction. Hemoglobin reacts with oxygen to form oxyhemoglobin, but the position of equilibrium depends on the concentration of oxygen present. The lungs contain a high concentration of oxygen, which makes the formation of oxygen there desirable; in the other tissues, the concentration of oxygen remains low, which favors the release of oxygen from oxyhemoglobin.

Acidosis

The production of acids by ordinary metabolic processes can lower the pH and prevent the formation of oxyhemoglobin. This reduces the amount of oxygen supplied to body tissues--a condition known as acidosis--causing fatigue and headache.

Carbon Monoxide

Carbon monoxide reacts with haemoglobin almost irreversibly. This effectively means that there is very little hemoglobin left to react with oxygen, starving the tissues of oxygen. This explains why carbon monoxide constitutes such a threat, even at low concentrations.

References

• Aus-e-Tute: The Chemistry of Blood
• University of Bristol: Hemoglobin