Blood group: characteristics and compositions

Between 5 and 6 liters of blood circulates in the veins of an adultBut minimal loss of this fluid can have fatal consequences. The cardiovascular system performs essential tasks for the rest of the cells, such as transporting nutrients and oxygen, as well as removing residual components.

In addition, blood is the means of transport that cells of the immune system can use to move quickly to a damaged area, which is why donation is crucial for the treatment of patients, but how does organ transplantation work? , there are certain requirements that must be taken into account before receiving blood.

And this is it there are different types of blood and not all of them are compatible with each other. Poor reception of this substance generates a rejection reaction in the patient which can be fatal.

    Blood components

    The blood is a substance made up of four main elements:

    1. Erythrocytes or red blood cells

    Also called red blood cellsThese are cells responsible for transporting oxygen from the lungs to the rest of the body and, in turn, transporting carbon dioxide from the cells to the lungs, for elimination. They are loaded with hemoglobin, which is responsible for the characteristic red color of the blood.

    2. Leukocytes

    Commonly known as white blood cells, It is a set of cells that are part of the immune system and whose function is to protect the body against harmful agents.

    3. Platelets or platelets

    These are fragments of cells that circulate in the blood. Their function is to act on coagulation (stop blood circulation) and in healing ruptured blood vessels to minimize losses.

    4. Plasma

    It is the liquid part of the blood; it is essentially composed of water and proteins. It provides a means of transport, while participating in immune defense (immunoglobulins or antibodies) and coagulation (coagulation factors). When the clotting factors are removed, the plasma becomes serum.

      Blood groups (blood group)

      Blood groups or blood groups, Are defined by a number of characteristics present on the surface of erythrocytes, such as proteins or carbohydrates, which, in a foreign body, can be recognized as an antigen.

      The concept of antigen responds to any substance that the immune system can recognize as unknown, Thus initiating a defensive response in front of her. The tool used by leukocytes (especially B lymphocytes) is the manufacture of antibodies which bind to the antigen to label it and facilitate its attack.

      With the joint observation of these antigens and antibodies, 32 systems have been identified to date which make it possible to differentiate the different blood groups. Despite this, these are two of the best known and used: the AB0 system and the Rh factor. But keep in mind that they are not the only ones, there are other systems like the MNS, the Duffy or the Diego.

      AB0 system

      It is the first system discovered to differentiate blood groups, and it is still one of the main ones today. In this case, it is divided into four blood groups: A, B, AB and 0. The AB0 system was first described by biologist Karl Landsteiner in 1901, earning it the Nobel Prize for Medicine in 1930.

      This is based on the presence or absence of a carbohydrate in the cell membrane of erythrocytes. Although it is not exclusive to these cells, on the contrary, it is distributed in other types of cells, so it is also important in organ transplantation.

      The incompatibility is due to the fact that A has antibodies against B, and vice versa, While in the case of AB this type of blood does not offer any problems (because it presents both classes), while the 0 (which has the absence of the mentioned carbohydrate) has as many antibodies against A as against B. The greatest mortality in blood transfusions is due to errors in identifying this blood group.

      Rh factor

      It is the second most used system, and in this case, blood groups are divided into Rh positive or negative. This categorization is based on the presence (positive) or absence (negative) of a single protein in the erythrocyte membrane.

      This blood group delimitation criterion was also discovered by Landsteiner with Alexander S. Wiener in 1940, and described for the first time in rhesus macaques; hence its name.

      The incompatibility is due to the fact that negative type has antibodies against positive type, But not the other way around, i.e. the positive type can receive Rh negative blood.

      Importance of donating blood

      Blood groups have a demographic distribution, the most common being type 0+, while the least common is type AB. This is an important fact in the field of giving.

      Usually 0- is the most searched blood group for he is known as the universal donor, A can be used for all transfusion cases because it has no antigen (neither A, nor B, nor Rh +). However, people with 0- cannot receive dangerous blood of the same type because they all have antibodies against the other types.

      En instead, AB + was called “the universal receptor”, As it can receive any type of blood, not presenting any of the antibodies against the rest. The problem is that it can only be given to people of the same gender because it has all kinds of antigens.

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