The red blood pigment hemoglobin gives the red blood cells their color and also fulfills important functions in the respiratory chain. The hemoglobin contains a divalent iron compound that can bind to oxygen. It is therefore also referred to as oxygen-affine. Oxygen binding of the red blood pigment is called oxygenation in medical terminology.
The blood thus fulfills the task of a transport medium during breathing and brings the oxygen to individual organs and tissues. Oxygen is present in the blood both in the bound and in the physically dissolved form. The dissolved form plays a role in particular for the exchange of oxygen between the lung alveoli and the plasma. Also, the oxygen exchange between the blood plasma and the interstitium is dependent on dissolved oxygen, since this process is realized via diffusion.
However, oxygen is only sparingly soluble. Hemoglobin-bound oxygen transport, despite its limited solubility, maintains vital oxygen supply to the cell.
During oxygenation, oxygen binds to hemoglobin. As a result, the molecule changes its conformation, ie the spatial arrangement. In this process, especially the central iron atom of the blood pigment changes its position. Thus, the binding reaches a dynamic functional state. It comes with the oxygenation so not to a real oxidation or chemically complex reaction.
Unbound hemoglobin is also referred to as deoxyhemoglobin and appears as a strained T-form. Only by binding to oxygen atoms is the blood dye transferred to the relaxed R-form, which is also known as oxyhemoglobin. For example, the affinity of hemoglobin for oxygen depends on factors such as the conformation of the molecules. In the relaxed R-form, the red blood pigment is more affine than in the strained T-form.
The pH also plays a role that should not be underestimated for the oxygen binding affinity of hemoglobin. As the pH increases, so does the binding affinity of hemoglobin. The temperature has as great an influence on the binding affinity of the red blood pigment. Thus, the affinity increases with decreasing temperatures and loses itself in a consequence of too high core temperatures. In addition to these factors, the binding affinity of hemoglobin also depends on the carbon dioxide concentration.
The dependence on the factors carbon dioxide content and ph value of the blood is summarized as a so-called Bohr effect. At high pH and low carbon dioxide content, there is high affinity. The concentration of oxyhemoglobin increases accordingly to these conditions. Consequently, the binding affinity decreases with high carbon dioxide content and low pH.
The circulatory system of the body naturally takes these factors into account when transporting oxygen. In the capillaries of the lung, for example, there is a low carbon dioxide content and relatively high pH. The binding affinity of hemoglobin is correspondingly high in the lungs. This leads to the oxygenation of the red blood pigment. Outside of the pulmonary capillaries there is thus a relatively high CO2 content at low pH. The binding affinity of hemoglobin decreases accordingly and releases the oxygen piece by piece, which is then absorbed by the tissues and organs.
This dissociation of oxygen from the hemoglobin molecules is called deoxygenation and is as important for oxygenation of the body as oxygenation.
In the case of carbon monoxide intoxication, hemoglobin oxidation is limited or even completely overridden. Because the binding affinity of hemoglobin to carbon monoxide is about 300 times higher compared to the binding affinity to oxygen. Thus, in the case of smoke poisoning, carbon monoxide accumulates in the shortest time on the hemoglobin and in this way gives rise to carboxyhemoglobin. As a result, there is a blockade for the oxygen uptake and the oxygen content drops in the blood piece by piece.
Strong CO poisoning therefore causes hypoxia, ie a general undersupply of body tissue and organs with oxygen. When the CO content in the blood reaches a certain percentage, the person becomes unconscious due to this undersupply. If the salary continues to increase after fainting, death occurs at a certain concentration. In sub-supplies with oxygen, body tissue dies irreversibly.
For the treatment of reduced oxygen concentrations in the arterial blood oxygen therapies are available. These therapies are also helpful in pulmonary embolism. The same applies to heart attacks, respiratory insufficiencies or heart failure. Many cardiopulmonary diseases are in danger of hypoxia.
The hypoxia also threatens an anemia, since there are too few red blood cells in the plasma in this disease. The less hemoglobin, the less oxygen can be transported in the bound form in the organs. Anemia can occur as a result of blood loss, but can also be caused by a lack of iron or folic acid.
Also with diseases of the blood formation it can come to anämischen phenomenons, which are accompanied under certain circumstances with further blood formation disturbances and other accompanying symptoms. Anemias are treated according to their cause and revert to deficiencies as soon as the underlying deficiency is resolved.Tags: