Pg 145

The four different blood groups

AB

ABO

• The proteins found on the surface of the RBC are also known as antigen.

Note: These antigens do not stimulate the lymphocytes to produce antibodies.

The four different blood groups

• Classification of blood types are based on the type of antigens found on the surface of red blood cells.

The four different blood groups

‘Natural antibodies’

• Natural antibodies found in our blood.

• Antigens react with antibodies.

Natural antibodies Antibodies Occurs naturally and always present in the body.

Produced only in the presence of foreign objects like bacteria/virus.

Agglutination of blood

• Clumping / agglutination of blood occurs when:– Antigen A reacts with antibody a– Antigen B reacts with antibody b

Agglutination of blood

• Blood clumps block up small blood vessels and obstruct the flow of blood.

What happens when different blood groups are mixed in blood

transfusion?

• Blood donors• Blood receivers• Agglutination of donor’s RBCs

Why is blood group AB called the universal acceptor?

• Absent of antibodies in the plasma. • No reaction with antigens on other RBCs.

• “AB – sounds like acceptor”

Why is blood group O called the universal donor?

• No surface antigen on blood group O. • Will not react with natural antibodies in other

blood group.

• Antibodies a and b in the donor’s plasma would be diluted by the recipient's blood.

• Hence no effects of the antibodies on the recipient's RBC.

In summary

Blood group Receive blood from

A A,O B B,O

AB A,B,AB,O O O

Testing for blood group

Unknown X

Antibody A Antibody B

Check for AgglutinationAntigen A – antibody aAntigen B – antibody b

Test Yourself [pg145]

a)X – Blood group BY – Blood group ABZ – Blood group O

b) Serum from A contains antibody B. reacts with antigen B found on RBC to cause clumping.

C) Blood group O

d) A, AB

e) No surface antigen to cause agglutination of RBC. Antibodies a and b in the donor’s plasma would be diluted by the recipient's blood.Hence antibodies has no effects on the recipient's RBC.

Test Yourself [pg145]