Deoxygenation is the dissociation of oxygen molecules from hemoglobin molecules in human blood. The body’s oxygen supply is built on a cycle of oxygenation and deoxygenation. In phenomena such as smoke inhalation, this cycle is disrupted.
What is deoxygenation?
Deoxygenation is the dissociation of oxygen molecules from hemoglobin molecules in human blood. Chemical deoxygenation involves the dissociation of oxygen atoms from an atomic bond. Medicine refers to the decay of oxygen bonds on hemoglobin. Hemoglobin is the red blood pigment that contains divalent iron atoms. In human respiration, hemoglobin serves as a transport medium thanks to this oxygen-affinity iron bond. All organs and tissues of the body need oxygen. The blood transports the oxygen atoms to the thinnest branches of the bloodstream and thus supplies all tissues. Oxygen has only limited solubility. Therefore, it is present in the blood plasma not only in free form, but also in hemoglobin-bound form. This binding is also called oxygenation and is the opposite of deoxygenation. The binding affinity of hemoglobin to oxygen changes in different environments of the body. When the affinity decreases, deoxygenation takes place. The oxygen atoms are thus delivered to the individual tissues and organs of the body. Bondless hemoglobin is also called deoxyhemoglobin. Analogously, oxygen-bound hemoglobin is called oxyhemoglobin.
Function and purpose
Oxygenation and deoxygenation play together in the human organism to provide vital oxygen to tissues. Physically dissolved oxygen, for example, plays a role in the exchange between the blood plasma and the alveoli of the lungs. Between the plasma and the interstitium, oxygen exchange takes place by diffusion. Physically dissolved oxygen also plays a role in this process. However, to maintain the oxygen supply to all cells, binding to hemoglobin is also a vital process due to its limited solubility. When hemoglobin is oxygenated, its conformation changes. With this change in position, the central iron atom in the red blood pigment rearranges spatially and hemoglobin assumes a dynamic functional state. Without oxygen binding, hemoglobin is actually deoxyhemoglobin and thus exhibits a strained T-shape. With oxygenation, the shape of hemoglobin changes to a relaxed R shape. We are then talking about oxyhemoglobin. The affinity of hemoglobin for oxygen changes with the particular shape and spatial arrangement of the molecules. In its relaxed form, the red blood pigment thus has a greater affinity for oxygen than in its tense form. The pH value also has an influence on the affinity. The higher the pH in the respective body environment, the higher the oxygen binding affinity of hemoglobin. In addition, temperatures influence the binding properties. For example, the binding affinity to oxygen increases with a drop in temperature. Besides, the oxygen binding affinity depends on the carbon dioxide content. This dependence on carbon dioxide concentration, together with the pH dependence, is called the Bohr effect. The binding affinity of hemoglobin to oxygen falls as the carbon dioxide level rises and the pH is low. Thus, when the carbon dioxide level is low and the ph is high, the affinity increases. For this reason, hemoglobin oxygenates in the alveolar capillaries of the lungs during respiration, because there is a decreasing carbon dioxide level and the blood pH increases. In contrast, relatively high CO2 concentrations at low pH values are present in the blood system of the wider body circulation. The binding affinity of the red blood pigment thus decreases. Oxygen dissociates from the molecules of hemoglobin and deoxygenation occurs. Therefore, without deoxygenation, the blood would not be an effective transport medium for oxygen. Indeed, if the oxygen molecules remained permanently bound to the iron of hemoglobin, neither the body tissues nor the organs would benefit from the transport.
Diseases and ailments
In carbon monoxide poisoning, the oxygen-binding function of hemoglobin is impaired. For example, if a patient has inhaled too much smoke in a fire scenario, carbon monoxide attaches to the iron molecules of hemoglobin instead of oxygen.As a result, there is less oxyhemoglobin in the plasma. There is hardly any oxygenation in the body, because the oxygen affinity of the red blood pigment falls with the CO concentration. Deoxygenation of hemoglobin is favored as the affinity falls. Hypoxia occurs. The body is then no longer supplied with sufficient oxygen. In the case of severe intoxication, we speak of anoxia. Such a phenomenon is the complete absence of oxygen in the tissues of the body. While anoxia is almost always associated with smoke inhalation, hypoxia can also be caused by anemia or embolism. Sickle cell anemia patients, for example, suffer from chronic anemia. Their abnormal hemoglobin tends to clump together, clogging blood vessels and failing to oxygenate adequately. Therefore, sickle cell anemia can also cause hypoxia. The same applies to the so-called alpha-thalassemia, in which the synthesis of alpha chains in the protein portion of hemoglobin is disturbed. In the context of hypoxia, there is always a disturbed cell metabolism in the body. The cells of the body are always damaged by the lack of oxygen. How severe the consequences of the deficiency supply are depends, for example, on how quickly it can be remedied. The administration of oxygen is an important treatment step for most deficiency diseases. For hematopoietic diseases or hemoglobin disorders, blood transfusions are usually essential.
