What Are Blood Groups Definition Types ABO and Rh Factor Explained
In the human body, blood plays a major role in the transportation of hormones, nutrients, respiratory gases, hormones, etc. It is known as the only fluid connective tissue, which is because blood cells develop connections between different organs.
Along with transportation, blood is also involved in different thermoregulation processes, maintains and regulates body temperature, pH and another body metabolism. As per scientists’ views and observations, the total volume of the blood in the human body should be about seven to eight per cent of the complete bodyweight, which will be about 5 to 5.5 litres or 1.5 gallons of blood.
What are Blood Groups?
Blood groups, also called blood types, can be defined as the grouping of blood and are based on the presence or absence of genetically derived antigenic substances on the surface of red blood cells (RBCs). The antigenic substances may either be carbohydrates, glycolipids, proteins or glycoproteins, depending on the blood type system.
Karl Landsteiner, an Austrian scientist discovered the ABO blood group system in the year 1900. He was awarded the Nobel Prize for this discovery of his.
A Blood group or blood type is a blood-classification, categorized on the basis of presence and absence of antibodies and genetically derived antigenic particles on the surface of RBCs. There are 4 main blood groups of human blood which are O, A, B, and AB, which is also called the ABO blood type. For a safe transfusion, a specific way should be followed to match the blood groups.
Blood Group A– Presence of antigen A on the RBCs and antibody B in the plasma.
Blood group B– Presence of antigen B on the RBCs and A antibody in the plasma.
Blood group AB– Presence of both antigen A and B on the red blood cells and lacks the antibody.
Blood group O– Absence of both antigen A and B on the red blood cells and presence of both the antibodies A and B in the plasma.
Know the Different Types of Blood Groups along with its Rh Factor.
There are numerous interesting facts about Blood Groups which we are not aware of. Some facts about the Blood Groups are listed in the points below.
Fact-No-1
A newborn baby has only one cup of blood in the whole body, whereas, the healthy adult has about 1.3 to 1.6 gallons or 4.0 to 5.0 litres of blood circulating inside their body
Fact-No-2
Blood type influences one’s personality, which can also affect your fertility and belly fat. Women with blood type O are more likely to deal with fertility issues.
Fact-No-3
The Red blood cells that do not contain either A or B antigens on their surface are normally found in the person with blood type O.
Fact-No-4
Anybody with good health, healthy weight and around the age of 17 years old can donate blood every 3 to 4 months.
Fact-No-5
By the process of blood transfusion, every year more than 4.5 million lives are saved
Fact-No-6
No one can get AIDS or any other infectious disease by donating blood and donating blood takes less than 15 minutes.
Fact-No-7
Human blood has no other substitute and it makes 7 to 8 percent of total body weight.
Fact-No-8
Transfusion with a blood group different from yours can lead to complications.
Fact-No-9
In ABO blood type, a transfusion of AB blood group can be given to a person who has blood type A, B and AB.
Fact-No-10
AB blood type is known to be the “universal recipient” because AB+ people can accept blood from any other blood type. AB- is the least common blood type, which is less than 1% of the population. An individual with AB- blood type can receive blood from all three negative blood types.
Fact-No-11
O blood type is called to be the “universal donor” because O+ is the most frequently occurring blood group in the ABO type. About 37 to 40 percent of the entire population are found with this blood type. O- is the rare blood group as it is found in 6 to 7 per cent of the total population.
Fact-No-12
A+ is the third most frequently occurring blood type in the ABO system. Thirty people out of hundred people have A+ blood type. A- is the rare blood type, which is less than 10 to 15 percent of the population has this blood type.
Fact-No-13
Both B+ and B- are rare blood types and less than 10 percent of the population has this blood type.
Fact-No-14
Like hair colour, texture, and eye colour, blood type is also inherited or passed genetically from our parents. Therefore, our blood group is based on the blood types of either mother or father.
Fact-No-15
Blood Types and Compatible Blood Type Donors
FAQs on Facts About Blood Groups and Their Importance in Transfusion
1. What are blood groups?
Blood groups are classifications of human blood based on the presence or absence of specific antigens on the surface of red blood cells (RBCs). The most important blood group systems are:
- ABO blood group system – based on A and B antigens
- Rh blood group system – based on the presence or absence of the Rh (D) antigen
These blood groups are essential for safe blood transfusion, organ transplantation, and pregnancy compatibility.
2. What are the different types of blood groups in the ABO system?
The ABO system has four main blood groups: A, B, AB, and O, based on specific antigens present on red blood cells. They are classified as:
- Group A – A antigen present, anti-B antibodies in plasma
- Group B – B antigen present, anti-A antibodies in plasma
- Group AB – Both A and B antigens present, no anti-A or anti-B antibodies
- Group O – No A or B antigens, both anti-A and anti-B antibodies present
This classification is crucial in preventing agglutination during blood transfusion.
3. What is the Rh factor in blood groups?
The Rh factor is a protein antigen called Rh (D) antigen found on the surface of red blood cells. Based on its presence or absence:
- Rh-positive (Rh+) – Rh antigen is present
- Rh-negative (Rh−) – Rh antigen is absent
The Rh factor is especially important during pregnancy and blood transfusions to avoid immune reactions such as hemolytic disease of the newborn.
4. How are blood groups inherited?
Blood groups are inherited genetically from parents through specific alleles of the ABO and Rh genes. The ABO blood group follows these inheritance rules:
- IA and IB are codominant alleles
- i is a recessive allele
A child receives one allele from each parent, which determines their blood type. The Rh factor is inherited separately and is usually dominant if at least one Rh-positive allele is present.
5. Why is blood group important for blood transfusion?
Blood group compatibility is essential in transfusion because mismatched blood can cause agglutination and hemolysis. If incompatible blood is transfused:
- Antibodies in the recipient’s plasma attack donor RBC antigens
- Red blood cells clump together
- This may lead to serious or fatal reactions
Therefore, proper blood typing and cross-matching are performed before every transfusion.
6. Who is the universal donor and universal recipient?
In the ABO and Rh system, O negative (O−) is considered the universal donor and AB positive (AB+) is the universal recipient. This is because:
- O− blood has no A, B, or Rh antigens, reducing risk of immune reaction
- AB+ individuals have no anti-A, anti-B, or anti-Rh antibodies
However, exact blood group matching is still preferred in clinical practice.
7. What happens if incompatible blood groups are mixed?
If incompatible blood groups are mixed, an immune reaction called agglutination occurs. During this reaction:
- Antibodies bind to foreign antigens on donor RBCs
- Red blood cells clump together
- Cells may rupture, causing hemolysis
This can lead to fever, kidney failure, shock, or even death, making compatibility testing critical.
8. Can a person’s blood group change over time?
A person’s blood group does not normally change because it is genetically determined. However, in rare cases, temporary changes may occur due to:
- Bone marrow transplantation
- Certain blood cancers like leukemia
- Severe infections affecting antigen expression
Under normal biological conditions, an individual’s ABO and Rh blood type remains constant throughout life.
9. What is hemolytic disease of the newborn (HDN)?
Hemolytic disease of the newborn is a condition where an Rh-negative mother produces antibodies against an Rh-positive fetus. This happens when:
- Fetal Rh-positive blood enters the mother’s bloodstream
- The mother forms anti-Rh antibodies
- These antibodies attack fetal red blood cells in subsequent pregnancies
HDN can be prevented by administering Rh immunoglobulin (RhoGAM) to the mother during and after pregnancy.
10. How is blood group tested in the laboratory?
Blood group testing is done using a method called blood typing, which detects specific antigens using known antibodies. The steps include:
- Mixing blood with anti-A, anti-B, and anti-Rh sera
- Observing for agglutination
- Identifying the blood group based on clumping patterns
This simple laboratory test ensures safe transfusion and accurate identification of ABO and Rh blood groups.
