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Bohr effect is a property of hemoglobin
Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
 first described in 1904 by the Danish physiologist Christian Bohr
Christian Bohr

Christian Harald Lauritz Peter Emil Bohr was a Denmark physician, and father of the famous physicist Niels Bohr, as well as the famous mathematician Harald Bohr....
 (father of physicist Niels Bohr
Niels Bohr

Niels Henrik David Bohr was a Denmark physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922....
), which states that in the presence of carbon dioxide, the oxygen affinity for dissociation of respiratory pigments, such as hemoglobin
Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
, decreases; because of the Bohr effect, an increase in blood carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 level or a decrease in pH
PH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
 causes hemoglobin
Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
 to bind to oxygen
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
 with less affinity.

This effect facilitates oxygen transport as hemoglobin binds to oxygen in the lungs, but then releases it in the tissues, particularly those tissues in most need of oxygen.






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Oxyhaemoglobin Dissociation Curve
Bohr effect is a property of hemoglobin
Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
 first described in 1904 by the Danish physiologist Christian Bohr
Christian Bohr

Christian Harald Lauritz Peter Emil Bohr was a Denmark physician, and father of the famous physicist Niels Bohr, as well as the famous mathematician Harald Bohr....
 (father of physicist Niels Bohr
Niels Bohr

Niels Henrik David Bohr was a Denmark physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922....
), which states that in the presence of carbon dioxide, the oxygen affinity for dissociation of respiratory pigments, such as hemoglobin
Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
, decreases; because of the Bohr effect, an increase in blood carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 level or a decrease in pH
PH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
 causes hemoglobin
Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
 to bind to oxygen
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
 with less affinity.

This effect facilitates oxygen transport as hemoglobin 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 bicarbonate molecules and 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 hemoglobin to the tissue, allowing the tissue to obtain enough oxygen to meet its demands (and raise its blood pH).

The dissociation curve
Oxygen-haemoglobin dissociation curve

The oxygen-haemoglobin dissociation curve plots the proportion of hemoglobin in its saturated form on the vertical axis against the prevailing oxygen tension on the horizontal axis....
 shifts to the right when carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 or hydrogen ion concentration is increased. This facilitates increased oxygen dumping. This makes sense because increased CO2 concentration and lactic acid
Lactic acid

Lactic acid , also known as milk acid, is a chemical compound that plays a role in several biochemistry processes. It was first isolated in 1780 by a Swedish chemist, Carl Wilhelm Scheele, and is a carboxylic acid with a chemical formula of C3H6O3....
 build-up occur when the muscles need more oxygen. Changing haemoglobin's oxygen affinity is the body's way of adapting quickly to this problem.

The lactic acid formed in muscle does not exist as such, since the pKa
Acid dissociation constant

An acid dissociation constant, Ka, is a quantitative measure of the strong acid in solution. It is the equilibrium constant for a chemical reaction known as Dissociation in the context of acid-base reactions....
 of the -COOH group in lactic acid is +2.86. The pH of muscle tissue is about 7.4, so according to the Henderson–Hasselbalch equation since pH >> pKa, lactic acid will be present not as H3C-CHOH-COOH but only as the ionized form H3C-CHOH-COO-.

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.

See also

Haldane Effect
Haldane effect

The Haldane effect is a property of hemoglobin first described by the Scottish people physician John Scott Haldane.Deoxygenation of the blood increases its ability to carry carbon dioxide; this property is the Haldane effect....


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