Blood typing

Composition

The word blood refers to a mixture of cells, enzymes, proteins, and inorganic substances.

The fluid portion of the blood is called the plasma and makes up 55% of blood’s composition

Within the plasma are the solid components such as red blood cells, white blood cells, and platelets; this makes up 45% of the composition.

Antigens

On the surface of each blood cell are millions of chemical structures called antigens

These antigens are responsible for blood types of the RBC’s

Blood types

There are more than 15 blood type systems that have been identified to date and of those the A-B-O and Rh systems are the most important.

Blood types are:A, B, O, and ABThose can be Rh+ or Rh- (also known as

antigen D)

Blood type distribution Blood types are different in distribution

throughout different populations but in the USA the percentages are:O 43% Rh+ 85%A 42% Rh- 15%B 12%AB 3%

Calculating Blood Types Type O+

.43 X .85 = .3655

.3655 X 100% = 36.55% of the population is type O+

Phenotype for blood type If an individual is A blood type that

means the individuals red blood cells have A antigens located on the surface…same with type B

Type AB has both antigens Type O has neither antigens The presence of type D antigen

indicates Rh + and the lack of D indicates Rh -

Blood typing chart

Antibodies

For every antigen there is a specific antibody and an antibody will react only with a specific antigen

If a serum containing antibody B, anti-B for short, is added to blood containing antigen B then a agglutination or clotting will occur

Testing for Blood type When testing for blood type of an unknown

source, Anti-A and Anti-B sera are used to test for agglutination as follows

Anti-sera A Anti-sera B Antigen present Blood type

       

+ - A A

- + B B

+ + A and B AB

- - Neither O