Oxygen transport represents a physiological process in the organism in which oxygen is transported from the alveoli to all body cells. During this process, complex physical and chemical processes occur that are closely interrelated. If these processes are disturbed, the body may be undersupplied with oxygen.
What is oxygen transport?
Oxygen transport represents a physiological process in the organism in which oxygen is transported from the alveoli to all the cells of the body. Carbohydrates, fats and proteins are oxidized to produce energy in the organism. This oxidation is also called combustion and requires oxygen as a reaction partner. However, oxidation must take place in all body cells for energy production, so there is a need to transport the oxygen required for this purpose in the air from the pulmonary alveoli evenly to all areas of the body. This can only be done by oxygen transport. Oxygen transport depends on certain physical and chemical parameters and factors. Among other things, there are two possible forms of transport. Most of the oxygen is reversibly bound to an iron atom in hemoglobin via a complex bond. To a lesser extent, oxygen may also be dissolved directly in the blood plasma. Oxygen diffuses from the pulmonary alveoli (air sacs) into the blood plasma. The higher the partial pressure in the alveoli, the more oxygen also enters the blood. The oxygen-rich blood first flows into the left ventricle and from there is transported as arterial blood via the arteries to the target organs and target cells. Both the oxygen reversibly bound to hemoglobin and the oxygen freely dissolved in the blood plasma are released there and enter the individual cells. There, the combustion product carbon dioxide is formed, which, together with the unconsumed oxygen, is returned to the pulmonary artery via the venous blood circulation. In the lungs, carbon dioxide is released and exhaled, while at the same time there is an uptake of new oxygen in the blood via the alveoli.
Function and purpose
The most important function of oxygen transport is to distribute the inhaled oxygen evenly to all the cells of the body. This represents the greatest challenge of oxygen transport. In the body cells, the energy carriers carbohydrates, fats, and proteins are oxidized with the release of energy. Energy sustains all life processes. If the supply of oxygen were to be stopped, the cells concerned would therefore die. When there is a higher demand for oxygen, such as during physical work, more oxygen must therefore be transported than during periods of rest. In such a case, the difference in concentration of oxygen between the lung alveoli and the blood plasma must be higher than when the demand is lower. Accordingly, the respiratory and heart rates increase in this case. The partial pressure of oxygen increases. Thus, more oxygen is dissolved in the blood plasma or bound in hemoglobin. Hemoglobin forms complex compounds with iron, which can bind even more oxygen molecules after the first oxygen molecule has been absorbed. The basic unit of hemoglobin, heme, represents an iron-II complex with four globin molecules. The iron atom of heme can bind up to four oxygen molecules. When the first oxygen molecule is bound, the conformation of the heme is changed to actually facilitate further oxygen uptake. The color of the hemoglobin changes from dark to bright red. The loading of hemoglobin depends on several physical and chemical factors that are closely interrelated. For example, there is a cooperative effect that results in an increasing oxygen affinity of hemoglobin at its higher loading. Meanwhile, a low PH at a high carbon dioxide partial pressure favors a complete release of oxygen from hemoglobin. The same is true with an increase in temperature. The changes in these physical conditions take place in the context of different activity states of the body, so that with a normally functioning oxygen transport, the oxygen supply of the organism is optimally tuned.
Diseases and ailments
When the body no longer receives an optimal supply of oxygen, functional impairment and even failure of the affected organs can occur. Oxygen cannot be stored in the body. Therefore, active oxygen transport must be constantly maintained for all life processes. However, if the oxygen supply is interrupted for just a few minutes, irreversible organ damage or even organ failure are often the result. A prerequisite for the smooth transport of oxygen is first of all an optimally functioning circulatory system. Disorders of the circulatory system caused by arteriosclerotic vascular changes, blood clots or blockages can significantly impair the oxygen supply to the body. When blood vessels are constricted, blood pressure rises in order to continue supplying the organs with oxygen. In the case of heart attacks, strokes or pulmonary embolisms, the blood supply and thus the supply of oxygen can be completely blocked. Other causes of an undersupply of oxygen to the body are various heart diseases that are associated with a restriction of the pumping capacity. These include general cardiac insufficiency, cardiac arrhythmias or inflammatory heart diseases. As a result, insufficient blood ultimately reaches the corresponding target organs. However, an undersupply of oxygen to the organism can also result from blood diseases or certain poisonings. For example, the molecule carbon monoxide competes with the oxygen molecule for binding sites in hemoglobin due to a similar molecular structure. Carbon monoxide poisoning is therefore nothing more than an oxygen deficiency that can lead to death by suffocation. Furthermore, there are various genetic blood diseases that affect the structure of hemoglobin and cause chronic oxygen deficiency. Sickle cell anemia can be mentioned here as an example. Other forms of anemia (anemia) also result in a constant lack of oxygen.
