It is essential to know your blood group as it saves time in case of emergencies. Blood transfusions are now an important part of any surgical interventions and healthcare procedures. Hence, it is important for an individual to know his blood group. Similarly, pregnant women must be aware of their blood groups as the emergency can stage at any moment.
Blood Composition
Different components come together to form blood. These include plasma, blood cells, red cells (erythrocytes), white cells (leukocytes) and platelets. Each serve different functions and are extremely essential for the proper working of the body system.
Definition of Blood Group
Red blood cells or erythrocytes contain antigens on their surface, which are a type of proteins. The plasma is known to carry antibodies that attack certain antigens when present.
Depending upon the type of red blood cell antigens, the blood groups are classified. The most important type includes the ABO and the rhesus type.
ABO Blood Groups
ABO was discovered first and hence is considered primary attribute for evaluating the different types of blood groups. The distribution of the antigens in the red blood cells is as below:
- Red blood cells with type A antigens on their surface also have anti-B antibodies in the plasma
- Red blood cells with type B antigens on their surface also have anti-A antibodies in the plasma
- Red blood cells with both A and B antigens on their surface do not have antibodies of B or A in the plasma
- If both the A and B antigens are absent on the surface of the red blood cells, the plasma contains both anti-A and anti-B antibodies
The Rhesus Types
People with rhesus antigens on the surface of their red blood cells are considered Rhesus (Rh) positive. Around 3 in every 20 people do not contain the rhesus antigens in their red blood cells and hence are said to be Rh negative.
Names of Blood Groups
You inherit the genetic makeup of your DNA from your parents. Similarly, the genetic makeup is also responsible for determining the type of antigen present in your red blood cells. That is why; blood group test is considered important evidence in paternity test.
The classification of blood groups is as follows:
- If you have rhesus and A antigens you are A positive
- If you have A antigens and no rhesus antigens then you are A negative
- If you have B and rhesus antigens then you are B positive
- If you have B antigens but no rhesus antigens then you are B negative
- If you have both A and B antigens, plus rhesus antigens then you are AB positive
- If you have both A and B antigens, but no rhesus antigens then you are AB negative
- In case you do not have both the A and B antigens, but have the rhesus antigens you are O positive
- In case you do not have any of the antigens (A, B and Rh) you are O negative
Minor Classification Based on Other Antigens
Many other antigens are also present on the surface of the red blood cells. However, they are not as important as the A, B and the Rh antigens and are considered as minor groups.
Universal Donor and Recipient
While carrying out blood donation, Rh-negative blood is given to Rh-negative patients. However, Rh-positive patients can receive both the Rh-positive as well as Rh-negative blood.
- Type O negative blood group is known as universal red cell donor as it is compatible with all types of blood groups.
- Type AB blood group is known as universal plasma donor
- Type AB positive blood group is known as universal recipient because a person with this blood group can receive any type of blood.
Thus, the knowledge about the blood groups is extremely important as it plays a major role during blood transfusion in an emergency.
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