Bohr effect
From Free net encyclopedia
The Bohr effect is a property of haemoglobin first described by the Danish physiologist Christian Bohr in 1904. Because of the Bohr effect, an increase in blood carbon dioxide level, a decrease in pH or increased temperature causes haemoglobin to bind to oxygen with less affinity.
This effect facilitates oxygen transport as haemoglobin binds to oxygen in the lungs, but then releases it in the tissues, particularly those tissues in most need of oxygen. When a tissue's metabolic rate increases, its carbon dioxide production increases. The carbon dioxide is quickly converted into acidic protons by the enzyme carbonic anhydrase:
CO2+ H2O → H+ + HCO3-
This causes the pH of the tissue to decrease, and so increases the dissociation of oxygen from haemoglobin, allowing the tissue to obtain enough oxygen to meet its demands.
The dissociation curve shifts to the right when carbon dioxide concentration, temperature, or hydrogen ion concentration is increased. Therefore higher oxygen partial pressure is required for the same degree of saturation of haemoglobin.
In the Hiroshima variant haemoglobinopathy the Bohr effect is diminished so the haemoglobin has a higher affinity for oxygen and tissue may suffer minor oxygen starvation during high work.