Blood types: characteristics and compositions

The Blood groups are useful to know the compatibilities and possible dangers in the donation.

Between 5 to 6 liters of blood circulate in the veins of an adult, but the slightest loss of this fluid can have fatal consequences.However, the slightest loss of this fluid can have fatal consequences. The cardiovascular system carries out essential tasks for the rest of the cells, such as the transport of nutrients and oxygen, as well as the removal of residual components.

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

The fact is that there are different types of blood and not all of them are compatible with each other.. A poor reception of this substance generates a rejection reaction in the patient that can be fatal.

Components of blood

Blood is a substance composed of four main elements:

1. Erythrocytes or red blood cells

Also called red blood cellsThey are cells responsible for transporting oxygen from the lungs to the rest of the body, and in turn transport carbon dioxide from the cells to the lungs for elimination. They carry hemoglobin, responsible for the characteristic red color of the blood.

2. Leukocytes

Commonly known as white blood cellsThese are a group of cells that are part of the immune system and share the function of protecting the organism against harmful agents.

3. Platelets or thrombocytes

These are cell fragments that circulate in the blood. Their function is to act in the coagulation (to stop blood circulation) and in the healing of blood vessel ruptures to minimize blood loss. to minimize losses.

4. Plasma

This is the liquid part of the blood; it is basically made up of water and proteins. It provides a means of transport, as well as participating in immune defense (immunoglobulin or antibodies) and coagulation (coagulation factors). When the clotting factors are removed, the plasma is called serum..

Blood groups (blood types)

The blood types, or blood groupsare defined by a series of characteristics found 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 to it.thus initiating a defensive response against it. The tool used by leukocytes (specifically B lymphocytes) is the manufacture of antibodies that bind to the antigen to mark it and facilitate the attack against it.

By observing these antigens and antibodies together, 32 systems have been identified to date that allow differentiation between different blood types. However, two are the best known and most widely used, two are the best known and most widely used: the AB0 system and the Rh factor.. But we must bear in mind that they are not the only ones, there are other systems such as the MNS, the Duffy or the Diego.

AB0 system

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

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

The incompatibility is due to the fact that A presents antibodies against B, and vice versa, whereas in the case of AB, antibodies against B are present.In the case of AB, this type of blood does not offer problems (since it presents both types), while the 0 (which has the absence of the carbohydrate mentioned) has both antibodies against A and against B. The higher mortality in blood transfusions is due to failures in the identification of this blood group.

Rh factor

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

This criterion for demarcating blood types was also discovered by Landsteiner together with Alexander S. Wiener in 1940, and first described in rhesus macaques; hence its name.

The incompatibility is due to the fact that the negative type presents antibodies against the positive type, but the reverse is not true.The incompatibility is due to the fact that the negative type has antibodies against the positive type, but the reverse is not true, i.e., the positive type can receive Rh-negative blood.

Importance in blood donation

Blood types 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 donation.

Generally, the 0- is the blood type most in demand, as it is known as the universal donor. it is known as the universal donorThe 0- type can be used for any transfusion case because it does not have any antigen (neither A, nor B, nor Rh+). However, people with 0- cannot receive blood except of the same type, because they present all the antibodies against the rest of the types.

En contrast, AB+ has been called "the universal recipient", since it can receive any type of blood.because they can receive any type of blood, since they do not present any of the antibodies against the rest. The downside is that it can only donate to people of the same type, because it has all the types of antigens.