Erythrocytes are called cells whose role is the transport of oxygen and carbon dioxide. In humans and mammals, these are non-nuclear shaped elements that are formed by the red bone marrow. Performing their function, they acquire more and more damage. Over time, they, unable to recover, modified and deformed, must be destroyed.
RBC destruction process
Due to the presence of a natural mechanism of cell aging, the life span of red blood cells is 120 days. This is the average time during which the cells are able to perform their function. Although theoretically, an erythrocyte can die immediately after leaving the bone marrow. The reason is mechanical damage that occurs, for example, during a long march or in case of injuries. Then destruction occurs either in the hematoma or inside the vessels.
The natural process of destruction that regulateslifespan of erythrocytes, takes place in the spleen. Macrophages recognize cells with a small number of receptors, which means that they have been circulating in the blood for a long time or have significant damage. Then the formed element is digested by a macrophage, which separates the heme (iron ion) from the protein part of hemoglobin. The metal is sent back to the bone marrow, where it is passed on as a feeder cell to dividing proerythroblasts.
Features of human erythrocyte life
Theoretically, the lifespan of human erythrocytes could be infinitely long under certain conditions. First, there should be no mechanical resistance to blood circulation. Secondly, the erythrocytes themselves should not be deformed. However, in the human vascular bed, these conditions cannot be met.
When red blood cells move through the vessels, they withstand multiple mechanical impacts. As a result, the integrity of their membranes is violated, some surface receptor proteins are damaged. Moreover, the erythrocyte does not have a nucleus and organelles intended for protein biosynthesis. This means that the resulting defects the cell can not restore. As a result, spleen macrophages "catch" cells with a small number of receptors (which means that the cell has been circulating in the blood for a long time and is possibly seriously damaged) and destroy them.
The need to destroy "age" red blood cells
The actual lifespan of red blood cellsa person is about 120 days. During this period, they receive a lot of damage, due to which the diffusion of gases through the membrane is disturbed. Because the cells in terms of gas exchange become less efficient. Also "elderly" erythrocytes are unstable cells. Their membrane can collapse right in the bloodstream. This will result in the development of two pathological mechanisms.
Firstly, the released hemoglobin that enters the bloodstream is a high molecular weight metalloprotein. Without the natural enzymatic process of substance involution, which normally can only occur in spleen macrophages, this protein becomes dangerous for humans. It will enter the kidneys, where it can damage the glomerular apparatus. The result will be the gradual development of kidney failure.
Example of pathological destruction of erythrocytes
Provided that a certain amount of red blood cells is gradually destroyed in the vascular bed, the concentration of hemoglobin in the blood will be approximately constant. This means that the kidneys will also be damaged constantly and progressively. Therefore, another meaning why erythrocytes are destroyed in advance is not only the removal of "old" forms, but the prevention of their destruction in the blood.
By the way, an example of toxic damage by a metalloprotein can be clearly seen on the example of a crash syndrome. There is a large amount of myoglobin (substancesextremely close to hemoglobin in structure and composition) enters the blood due to muscle necrosis. This damages the kidneys and leads to multiple organ failure. In the case of hemoglobin, a similar effect should be expected. Therefore, it is important for the body to eliminate "old" cells in time, and therefore the life expectancy of erythrocytes is maximum about 120 days. What about animals?
Life span of red blood cells in animals
In animals of different classes, blood cells are different. Because their lifespan is also different from the human. But if we take mammals as an example, there are many similarities. The red blood cells of mammals are almost the same as those of humans. This means that the lifespan of red blood cells is about the same.
The situation is different in amphibians, reptiles, fish and birds. All of them have nuclei in their red blood cells. This means that they are not deprived of the ability to synthesize proteins, even if this property is not the most important thing for them. Much more important is the ability to restore their receptors and damage. Therefore, the life span of erythrocytes in animals is somewhat longer than in humans. It is difficult to answer how much higher it is, because they did not conduct studies with labeled cells as unnecessary.
The importance of human research
Until some time, the knowledge that the life span of erythrocytes in human blood is 120 days did not help practical medicine in any way. However, after the discovery of the ability of hemoglobin to bind tosome substances, new possibilities have opened up. In particular, a method for determining glycated hemoglobin is widely practiced today. This provides information on how high the glycemic level has risen in the last three months. This greatly helps in the diagnosis of diabetes, as it allows you to find out how blood glucose rises.
