Hemocatheteresis: what is it, characteristics and functioning?

Let's see what hemocateresis, a biological process of red Blood cell recycling, consists of.

Erythrocytes or red blood cells are the most common cell types in the blood. Because they contain hemoglobin, these cells are responsible for transporting oxygen in the blood to the different types of tissues and organs in our body.

Having such an essential function, it is not surprising that there are about 5,000,000 erythrocytes per cubic millimeter of blood, i.e. 1000 times the number of white blood cells.

These cells are very characteristic, as they lack a nucleus and mitochondria and can therefore only obtain energy by degrading glucose. Their functionality is very limited, as they cannot synthesize proteins, which is why erythrocytes are literally considered as "hemoglobin sacks".

Hematopoiesis is the process by which these unique cell types are synthesized. This mechanism is well known in biological and medical fields, as it is one of the first pathways to be studied because of its physiological importance. Something much less widespread is, on the other hand, the process by which the "retired" red blood cells are eliminated. Today we tell you all about hemocateresis or erythrocytosis.. Do not miss it.

What is hemocateresis?

From a simple physiological point of view, we can define hemocathetosis as the process by which red blood cells (erythrocytes) in the process of degeneration are eliminated from the spleen and liver.. These cell types have a half-life of 120 days and, when they age, are destroyed by cellular apoptosis mechanisms.

We have introduced a striking term worth dwelling on: apoptosis. We can define this physiological process as a "programmed cell death", a set of biochemical reactions that occur in multicellular living beings in order for the degenerated cell to die in order for the degenerated cell to die without causing any damage to the organization of the tissues to which it belongs.

The process of apoptosis is completely normal because, without going any further, epidermal cells are in continuous replacement. What else is dandruff? Studies estimate that approximately 3,000,000 cells die in our organism every second in a natural way, a value that increases in the case of injuries.This figure increases with injuries or serious infectious processes such as necrotizing fasciitis.

In any case, erythrocytes, red blood cells or red blood cells (whatever you want to call them) are anything but normal cells. Therefore, we dedicate the following lines exclusively to elucidate how these aging entities eventually disappear from our body.

The fascinating process of erythrocytosis

As mentioned above, humans have an enormous number of red blood cells per liter of blood, since they represent 10% of the total cell volume in all our tissues. Circulating erythrocytes have a half-life of 120 days, but they are continuously exposed to physiologically demanding factors, such as oxidative stress in the lungs and hyperosmotic conditions as they pass through the kidneys several times a day.

Thus, there comes a time when the "life" of these cell bodies is exhausted. As with any process involving the presence of cells, their generation and replacement must be strictly regulated, which is why in many cases the very genesis of erythrocytes is considered to be a partial apoptosis (as nuclei and mitochondria, for example, are lost in their differentiation). (since the nucleus and mitochondria, for example, are lost in their differentiation). The fate of these cells is sealed from the beginning.

Let's keep things simple: when an erythrocyte ages, a number of immunoglobulin-like proteins (antibodies) IgG bind to it. The function of these antibodies is to "signal" to the aged red blood cell so that Kupffer cells in the liver can phagocytose them. The main molecular mechanisms involved that signal this "aging" of the erythrocyte are as follows:

• The decrease in the energy charge of the circulating red blood cell.
• The decrease in the reducing power of the erythrocyte.
• Presence of osmotic stress.

One of these 3 cellular mechanisms (or all 3 at the same time) are the ones that promote the event of hemocateresis, i.e., that the senescent red blood cell itself is phagocytized and does not rejoin the circulating blood.

Once phagocytosed...

Once these red blood cells have been phagocytized in the spleen, liver and bone marrow, the hemoglobin is recycled. The "globin" portion, i.e. the protein part, is recycled and broken down into amino acids that can be used for the synthesis of other molecules essential to the organism. The "heme" portion, on the other hand, is a non-protein prosthetic group, which is why it cannot be broken down into useful forms so easily.

Therefore, this "heme" group is broken down into useful forms, this "heme" group dissociates into iron and bilirubin, the latter moleculeThe latter molecule may be familiar to more than one reader. Bilirubin is a waste product that is secreted by the bile in its conjugated form, so we can say that it is released into the duodenum by the digestion process. On the other hand, iron can be stored in the form of certain specific molecules or return to the spinal cord, where it will again form part of new red blood cells.

But it doesn't end there. Bilirubin passes through the small intestine, but in the large intestine bacterial colonies transform it into urobilinogen. Part of this compound is reabsorbed into the blood and excreted in the urine, while another part is excreted in the feces (in the form of stercobilin), a pigment that gives the stool its characteristic brown color.

After briefly following this pathway, we can see how the body does not get rid of anything that is not completely useless.. Many of the components of the dead red blood cell end up being reused, while bilirubin is released with the bile at the level of the duodenum, serving in turn as part of a digestive precursor. Of course, the perfect machinery of the human body leaves nothing to chance.

Eryptosis VS apoptosis

As you can imagine, the death of a red blood cell is very different from the senescence of a normal tissue cell.. Typical events of apoptosis include nuclear condensation, DNA fragmentation, rupture of nuclear membranes, mitochondrial depolarization and many other events that cannot occur directly in red blood cells due to the lack of these structures.

Even so, it is necessary to keep in mind that both processes are relatively similar and that the purpose is common: to replace a group of cells whose useful life has come to an end.

Diseases associated with hemocateresis or erythrocytosis

Hemocateresis or erythrocytosis is not always a normal and programmed mechanism, because There are certain pathologies that can advance the death of red blood cells and their consequent degradation..

A clear example of this is malaria. More than 400,000 people die annually from this parasite (mainly Plasmodium falciparum), which is transmitted to humans by the bite of infected mosquitoes and ends up spreading to the bloodstream and infecting red blood cells. Once inside the red blood cells, the pathogens multiply and cause them to rupture prematurely, releasing even more parasites into the blood to infect more red blood cells.

All this leads to severe physiological disturbances causing anemia, bloody stools, chills, sweating, convulsions, headaches, and even coma and death.. Without treatment, up to 40% of those infected eventually die. This is a clear example of what happens when unscheduled hemocateresis or erythrocytosis occurs on a massive scale and the danger that this entails.

Another less aggressive but equally important example is iron deficiency. A lack of iron in the body makes the "heme" part of hemoglobin smaller and less efficient, which is why the red blood cell's half-life is reduced. From parasites entering the body to a lack of nutritional intake, the half-life or senescence pattern of red blood cells in our body can be disrupted.

Summary

As you may have read in these lines, hemocateresis or erythrocytosis is a process that is divided into two important phases: the signaling and phagocytosis of the senescent red blood cell and the various metabolic pathways that its components follow until they are reused or excreted in the urine and/or feces.

If we want to give you an idea of all this biochemical conglomerate, it is the following: red blood cells are atypical cells, which is why their senescence process is different from that of a cell present in any normal tissue.. Even so, the process of erythrocytosis and apoptosis seeks a concrete end, the elimination of cells that are no longer useful for the organism to replace them with new ones.

Bibliographic references:

• Escorza, M. A. Q., & Salinas, J. V. C. (2006). Eryptosis, erythrocyte apoptosis. Journal of Biochemical Education, 25(3), 85 - 89.
• Herlax, V., Vazquez, R., Mate, S., & Bakás, L. (2011). Eryptosis, the suicidal death of erythrocytes: mechanism and associated diseases. Acta bioquímica clínica latinoamericana, 45(2), 287 - 296.
• Malaria, Medlineplus.gov. Retrieved December 25 from https://medlineplus.gov/spanish/ency/article/000621.htm#:~:text=The%20malaria%20is%20caused%20by,form%20of%20par%20par%20C3%A1sites%2C%20called%20merozo%C3%ADtos.
• Manzur-Jattin, F., Moneriz-Pretell, C., Corrales-Santander, H., & Cantillo-García, K. (2016). Eryptosis: molecular mechanisms and their implication in atherothrombotic disease. Revista Colombiana de Cardiología, 23(3), 218 - 226.