Blood is an essential component of our body. It is through this body fluid that nutrients and oxygen can travel through our body to reach the cells. In addition, it transports metabolic waste products away from those same cells.
If blood works the same way for all human beings, scientifically there are distinctions. These distinctions have their origin years ago, in the attempt of the human being to master the technique of blood transfusion.
In this article, we are going to see what types of blood exist and what are groups A, B, O, and AB, as well as the Rh factor, known for making blood known as “positive” or “negative”.
Why are there different types of blood?
The old idea of replacing the lost blood of an injured person with the blood of another was always in the human imagination. Thus, over time, research on blood transfusions was able to improve, since rejection problems prevented scientific advances for a long time.
Finally, the different types of blood are collected by what is known as the ABO System. In 1902, the Austrian doctor Karl Landsteiner, together with other scientists, classified blood into types: A, B, O, and AB.
During the investigations, Dr. Landsteiner and his collaborators realized that some blood types, when mixed, generated serious reactions. Destruction of red blood cells or red blood cells was the main problem.
Ultimately the studies showed that the reaction was caused by a protein in plasma called agglutinin. This reacts with another protein present in red blood cells called agglutinogen.
Classification of blood groups
Throughout our lives, we have all suffered accidents of all kinds that have made us bleed. Bleeding can be superficial, which causes us to lose very little blood, or more serious, our body being able to lose a lot of blood as blood vessels and other tissues are very damaged.
Next, we will explain which are the different existing blood groups and understand the reason for their classification. We suggest that in the next blood test you ask what your blood group is, so you can already know which group you are from and know the peculiarities of your blood type in terms of compatibility.
Group A blood
The investigation concluded that a blood type called “A” has in its plasma a protein that causes red cell problems of the blood type called “B”. Thus, the protein, which is an agglutinin, was called anti-B agglutinin. Therefore, group A blood plasma cannot join with group B red cells.
Group B blood
The same thing happens with type B blood as with group A blood. Plasma from blood group B contains anti-A agglutinin, which reacts with the agglutinogen in red blood cells of type A. Therefore, group B blood plasma cannot join with group A red cells.
Group AB blood
AB blood does not contain agglutinins in its plasma, and therefore there is no problem between this plasma and the red blood cells. It is for this reason that people in group AB are considered universal recipients because if they need blood they have the possibility of receiving transfusions of any type of blood. On the other hand, people of blood group AB can only give blood to other people of blood group AB.
Group O blood
Red cells in group O blood do not have agglutinogens, but unfortunately, their plasma has both types of agglutinin: anti-A agglutinin and anti-B agglutinin. This implies that the person with group O blood can only receive blood from people of the same group O. Instead, this blood group is considered the universal donor, since all blood types can receive it.
Compatibility table between blood groups
Below we present a blood compatibility chart and explain it. It is essential to take into account which is the compatibilities between blood groups to guarantee blood transfusions without problems.
Here is a chart to help us understand compatibility issues. If you know your blood group, you will be able to see with which other blood groups there is blood affinity.
Group A compatibility
Blood group A blood can receive blood types A and O, and they can donate blood to blood groups A and AB.
Group B compatibility
Blood from blood group B can receive blood from groups B and O, and they can donate blood to groups B and AB.
Group AB compatibility
Blood of blood group AB can receive the blood of all types (A, B, AB, and O), but you can only donate to the same blood group AB.
Group O compatibility
Group O can only receive blood from the same group O, however, you can donate to all other types (A, B, AB, and O).
Positive or Negative Factor
So far we have talked about the blood groups that exist, but we still need another factor to know the complete classification of blood. If you have noticed before we talked about blood types but also groups. Why group? Is there more than one classification within each group?
The answer is yes, and it is that surely at some point in your life you have heard about something else. Surely you have noticed that, in addition to blood types, there is also talk of positive and negative blood.
What does it mean if the blood is positive or negative?
Whether the blood is positive or negative has nothing to do with whether the blood is “good” or “bad.” This characteristic of the blood is what we call the Rh factor.
The Rh system was discovered in 1940 by Austrian physicists Karl Landsteiner and Alex Wiener. In their experiments, they used Rhesus monkeys, hence the name “Rh factor”.
The experience was based on injecting blood from these monkeys into rabbits. The observers saw that the rabbits produce antibodies, which bind to red blood cells. In this way an agglutination of the red blood cells was produced, these being identified as antigens, that is, foreign agents.
The researchers called these antibodies anti-Rh or anti-Rhesus. So they researched humans. Among the blood of the subjects they analyzed, there were positive and negative responses. The blood of people who produced the anti-Rh antigen was called anti-RH positive, while that of people who did not produce it was called anti-Rh negative.
Blood compatibility with Rh factor
The Rh factor ends up being the other important factor in blood transfusions. A person with the Rh-positive factor cannot donate to an Rh-negative person, as it can cause a reaction by the antibodies and agglutinate the red blood cells.
In contrast, an Rh-negative person can give blood to an Rh-positive person because the donor does not have the antibodies. Therefore, Rh-negative blood can always give regardless of Rh factor, and Rh-positive blood type can always receive blood regardless of Rh factor.
Below we show a new table with the compatibility of whole blood, that is, including the Rh factor to the compatibility between blood groups already presented previously: