Blood Group Systems.

 

Introduction:

• Blood is a fluid connective tissue made of two components Plasma and Blood Cells.

• Blood performs many important functions in the body like, transportation, regulation and protection.

• Blood is thick in appearance and has a temperature slightly higher than body temp. and pH is 7.4.

Blood Group Systems:

• RBCs have different types of Antigens present on their surface.

• The body synthesises the antibodies against other types of antigens which are not present on the RBCs.

• The blood group systems are based on the types of antigen a person is having in RBCs.

• Most common blood group systems used are:

1. ABO System.

2. Rh System.

ABO System:

• The two types of antigens identified present on the RBC surface are Antigen A and Antigen B.

• The presence of these antigens gives rise to the blood group system as,

1. Blood Group A: Having type A Antigen on RBCs.

2. Blood Group B: Having type B Antigen on RBCs.

3. Blood Group AB: Having both  type A and B Antigens on RBCs.

4. Blood Group O: No type A & B Antigen on RBCs.

• The person of Blood Group A contains antibodies for Antigen B and hence when given blood of Blood Group B shows transfusion reaction.

• The person of Blood Group B contains antibodies for Antigen A and hence when given blood of Blood Group A shows transfusion reaction.

• The person with Blood Group AB produces no antibodies hence shows no reaction with any blood group and hence called as “Universal Recipient”..

• The person with Blood Group O produces both antibodies A & B hence can donate blood to all blood groups and hence is also called as “Universal Donor” however, The person should receive blood from a person having Blood Group O only.

Rh System:

• Also called the “Rhesus System.”

• It indicates the presence of the “Rhesus Factor”. (Rh Factor, D Antigen).

• It was first observed in the Rhesus monkey and hence the name was given.

• Individuals whose erythrocytes have the Rh antigens (D antigens) are designated Rh +ve while those who lack Rh antigens are designated Rh -ve.

Blood Transfusion: 

• A transfusion is the transfer of whole blood or blood components into the bloodstream.

• It is given to treat low blood volume (Hypovolemia), low Oxygen Carrying capacity of blood (Anaemia), low Platelet count (Thrombocytopenia).

• However, in an incompatible blood transfusion, antibodies from recipients blood attacks on donors RBCs causing Hemolysis (breakdown of RBCs).

• The free Hb in blood causes kidney problems.

• Infected blood products may transmit diseases such as AIDS (Acquired ImmunoDeficiency Syndrome), Hepatitis C & B.

• Blood groups compatibility is as given below,

Commonly Asked Questions:

1. Write a note on “Blood Group System”.

2. Write a short note on transfusion of blood.