Blood Groups

The blood in the human body seems to be the same in color but is different in terms of its characteristics.

The blood type has been divided into two main groupings, namely −

• ABO Grouping

• Rh Grouping.

Let us see in detail about these two main blood groups.

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ABO Grouping

The presence and absence of two surface antigens, namely, A & B on the surface of red blood cells (RBC), determines the ABO grouping.

Antigen− Antigen is a substance that activates the immune system to respond against that substance. Antigens can be bacteria, viruses, toxins, or any other foreign substance that enters the body from the outside.

In the same way, plasma also contains different antibodies according to the different blood types. Therefore, during the blood transfusion process, the blood of a donor is carefully matched with the recipient’s blood to avoid critical health problems.

Plasma− Plasma constitutes about 55% of the blood. The proteins and antibodies present in the plasma are used to treat many serious health conditions. Plasma plays a crucial function in fighting against many infectious diseases.

Given below is the table in which different blood groups and their receivers and donor types are mentioned.

Blood Group	Antigens	Antibodies	Can give blood (RBC) to	Can receive blood (RBC) from
AB	A and B	None	AB	AB, A, B,O
A	A	B	A and AB	A &O
B	B	A	B and AB	B & O
O	None	A and B	AB, A, B, O	O

From the above table, we can infer the followings points −

• Blood group AB contains antigens A and B and can donate blood to the same blood type only, that is AB but can receive blood from all the other blood groups, which can be AB, A, B, and O. Therefore, the blood of human beings with blood group AB can be called “universal recipients”.

• Blood group A contains antigens A, can donate blood to the blood group A and AB and can be received by the blood groups A and O.

• Blood group B contains antigens B, can donate blood to the blood group B and AB and can be a recipient to the blood groups B and O.

• Blood group O does not have antigens; therefore, it can be safely transmitted to the people of any other blood group. People having blood group O are known as “universal donors'' because they can give blood to AB, A, B, and O groups but can receive blood from O blood groups.

Rh Grouping

Rh group is based on the presence or absence of the Rh antigen on the cell membrane of the RBCs. The term ‘Rh’ comes from the rhesus monkey (a type of monkey). The blood of rhesus monkeys was used to determine the presence of Rh antigen in human blood.

The presence of Rh antigen in the human blood means the person is Rh positive (Rh+ve) and the absence or lack of Rh factor means the person is Rh negative (Rh+ve). It is crucial to determine the Rh factor before the blood transfusion as it may cause severe health problems.

A person who is Rh positive can receive blood from Rh negative individuals but an Rh negative person, if exposed to an Rh positive person, can form specific antibodies against the Rh antigen.

Example

If we take the case of pregnant women whose blood is Rh negative and if the fetus blood group is Rh positive, the two blood groups are separated by the placenta in the first pregnancy. However, during the delivery, there is a possibility of exposure to the mother’s blood and the blood present in the fetus, which might cause a problem in her subsequent pregnancies.

The reason behind this is the mother’s blood group, which is Rh negative when exposed to the foetus blood group, which means the Rh positive blood group, starts producing antibodies against Rh antigens. When the mother gets pregnant next time, there might be a risk of the leakage of the Rh antibodies present in the mother’s blood (Rh -) to the foetus (Rh +), which can destroy the foetal RBCs. This condition is known as erythroblastosis foetalis.

This condition can be avoided by monitoring the anti-Rh antibodies in the mother immediately after she delivers the first child.

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Key Takeaways

• The ABO grouping is determined by the presence or absence of two antigens A and B.

• The blood of human beings is divided into four groups namely A, B, AB, and O.

• Blood group AB is the universal recipient.

• Blood group O is the universal donor.

• Erythroblastosis foetalis is the condition in which the Rh antibodies present in the mother’s blood (Rh -) get leaked to the foetus (Rh +) and destroy the foetus RBCs. This condition can be fatal for the foetus and can cause jaundice or anaemia in the baby.

FAQs

Q1. What determines the ABO grouping?

Ans. The presence and absence of two surface antigens namely A & B on the surface of RBC determines the ABO grouping.

Q2. Name the blood groups under the ABO system.

Ans. The blood groups present under the ABO system are − A, B, AB, and O.

Q3. Difference between the universal donor and universal recipient.

Ans. Universal Recipient − Blood Group AB contains antigens A and B and can donate blood to the same blood type only that is AB, but can receive blood from all the other blood groups which can be AB, A, B, and O. Therefore, human beings with blood group AB can be called “universal recipients” which means they can receive blood from any other blood groups.

Universal Donor − Blood Group O does not have antigens, therefore it can be safely transmitted to the people of any other blood group. People having blood group O are known as “universal donors'' because they can donate blood to AB, A, B, and O groups but can receive blood from O blood groups only.

Q4. Define Antigens.

Ans. Antigen is a substance, which activates the immune system to respond against that substance. Antigens can be bacteria, viruses, toxins, or any other foreign substance that enters the body from the outside.

Q5. Which blood type does not contain either A or B antigens on their surface?

Ans. O blood groups do not contain either A or B antigens on their surface.

Q6. If the blood group ends in +(positive), what does that mean?

Ans. The presence of Rh antigen in the human blood means the person is Rh positive (Rh+ve). This means if the surface of the red blood cells has Rh factor (protein), the individual can be considered to have a (Rh+) blood group.

Q7. Which condition is responsible for erythroblastosis foetalis.?

Ans. The condition in which the mother’s blood group which is Rh negative when exposed to the foetus blood group means Rh positive blood group, starts producing antibodies against Rh antigens. When the mother gets pregnant next time, there might be a risk of the leakage of the Rh antibodies present in the mother’s blood (Rh -) to the foetus (Rh +) which can destroy the foetal RBCs, this condition is responsible for erythroblastosis foetalis.