Oxygenation refers to the binding of red blood pigment to oxygen molecules. The opposite is also called deoxygenation and occurs when blood CO concentrations are too high or ph too low. Progressive deoxygenation puts the oxygen supply to organs at risk in carbon monoxide intoxications.
What is oxygenation?
Oxygenation refers to the binding of red blood pigment to oxygen molecules. The red blood pigment hemoglobin gives red blood cells their color and also performs important functions in the respiratory chain. For this purpose, hemoglobin contains a divalent iron compound that can bind to oxygen. It is therefore also known as oxygen affinity. The oxygen binding of the red blood pigment is called oxygenation in medical terminology. During respiration, the blood thus fulfills the function of a transport medium, bringing oxygen to individual organs and tissues. Oxygen is present in the blood both in bound and in physically dissolved form. The dissolved form plays a role in particular for the exchange of oxygen between the pulmonary alveoli and the plasma. Oxygen exchange between the blood plasma and the interstitium also depends on dissolved oxygen, since this process is realized by diffusion. However, oxygen is soluble only to a limited extent. Hemoglobin-bound oxygen transport maintains the vital cellular supply of oxygen despite its limited solubility.
Function and purpose
During oxygenation, oxygen binds to hemoglobin. As a result, the molecule changes its conformation, or spatial arrangement. During this process, the central iron atom of the blood pigment in particular changes its position. Thus, the bond reaches a dynamic functional state. Thus, no true oxidation or chemically complex reaction occurs during oxygenation. Unbound hemoglobin is also known as deoxyhemoglobin and appears as a strained T-shape. Only when bound to oxygen atoms is the blood pigment converted to the relaxed R form, also known as oxyhemoglobin. The affinity of hemoglobin for oxygen thus depends on factors such as the conformation of the molecules. In the relaxed R-form, the red blood pigment has a greater affinity than in the relaxed T-form. The pH value also plays a role in the oxygen binding affinity of hemoglobin that should not be underestimated. As pH increases, so does the binding affinity of hemoglobin. Temperature has an equally large influence on the binding affinity of the red blood pigment. Thus, the affinity increases with decreasing temperatures and, as a consequence, decreases at too high core temperatures. In addition to these factors, the binding affinity of hemoglobin is also dependent on the carbon dioxide concentration. The dependence on the factors carbon dioxide content and ph-value of the blood is summarized as the so-called Bohr effect. At high pH and low carbon dioxide content, there is a high affinity. The concentration of oxyhemoglobin increases accordingly at these conditions. Consequently, the binding affinity decreases at high carbon dioxide content and low pH. The body’s circulatory system naturally takes these factors into account when transporting oxygen. In the capillaries of the lungs, for example, there is a low carbon dioxide content and relatively high pH. The binding affinity of hemoglobin is therefore correspondingly high in the lungs. This results in oxygenation of the red blood pigment. Outside the pulmonary capillaries, there is a relatively high CO2 content at a low pH. The binding affinity of hemoglobin decreases accordingly, releasing the oxygen bit by bit, which is then absorbed by the tissues and organs. This dissociation of oxygen from the hemoglobin molecules is called deoxygenation and is of similar importance to oxygenation for the body’s oxygen supply.
Diseases and medical conditions
In carbon monoxide intoxication, the oxidation of hemoglobin is impaired or even completely abrogated. This is because the binding affinity of hemoglobin to carbon monoxide is about 300 times higher compared with the binding affinity to oxygen. Thus, in the event of smoke inhalation, carbon monoxide accumulates on the hemoglobin in a very short time, thus giving rise to carboxyhemoglobin.As a result, there is a blockage to oxygen uptake and the oxygen content in the blood drops bit by bit. Severe CO poisoning therefore triggers hypoxia, i.e. a general undersupply of oxygen to the body tissues and organs. When the CO content in the blood reaches a certain percentage, the affected person faints due to this undersupply. If the level continues to rise after fainting, death occurs above a certain concentration. When there is an undersupply of oxygen, body tissue dies irreversibly. Oxygen therapies are available to treat decreased oxygen concentrations in arterial blood. These therapies are also helpful for pulmonary embolism. The same is true for myocardial infarctions, respiratory insufficiencies, or heart failures. Hypoxia is a threat in many cardiopulmonary diseases. Hypoxia is also imminent in anemia because there are too few red blood cells in the plasma in this condition. Therefore, the less hemoglobin, the less oxygen can be transported to the organs in the bound form. Anemia can occur in the context of blood loss, but can also be caused by a deficiency of iron or folic acid. Anemic phenomena may also occur in hematopoietic disorders, which may be accompanied by other hematopoietic disorders and other accompanying symptoms. Anemias are treated depending on their cause and regress as part of deficiency symptoms once the causative deficiency is corrected.
