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UNIT 5 SEROLOGY
5.1 AN INTRODUCTION TO BLOOD
COMPONENTS OF BLOOD
Solid portion of the blood
1. Erythrocytes
• Red blood cells (RBC).
• Contain hemoglobin that transports the oxygen and carbon
dioxide.
• Concave in structure.
• Approximately 30 trillion in the blood.
COMPONENTS OF BLOOD
2. Leukocytes
• White blood cells (WBC).
• Provide immunity for the body and produce antibodies.
• There are 5 types of white blood cells.
• Approximately 430 billion in the blood.
COMPONENTS OF BLOOD
3. Thrombocytes
• Platelets (pieces of larger cells).
• Responsible for starting the clotting process by making fibrin to
form a clot.
COMPONENTS OF BLOOD
Liquid portion of the blood
1. Plasma
• Fluid portion of the blood that carries the RBC, WBC, and platelets.
• 55% of blood is the plasma.
• Made up of 90% water and 10% metabolites (salt, ions, and
proteins).
BLOOD TYPE
ABO blood classification system
1. Antigens
• Proteins found on the surface of every RBC.
• There are over 100 different antigens in the human blood.
• Two of the antigens, labeled as A and B, are the ones used on the
RBC surface to determine blood type.
•
•
•
•
If antigen A is present a person is A blood type.
If antigen B is present a person is B blood type.
If both antigens A & B are present a person is AB blood type.
If neither antigens A & B are present a person is O blood type.
BLOOD TYPE
2. Antibodies
• Manufactures by some of the WBC and found in the blood serum.
• Function is to attack any invader (antigen) that enters the bloodstream that
does not belong in your system.
• A person has antibodies again antigens that are not found on the surface of
their own RBC.
3. Rh Factor (Rhesus factor)
• Antigen found on the surface of a RBC.
• If a person has the Rh antigen they are Rh positive (Rh+).
• If a person does not have the Rh antigen they are Rh negative (Rh-).
DETERMINATION OF BLOOD TYPE
• Your blood is tested by adding blood cells of a known type.
• Remember, your blood has antibodies for the other antigens. These
antibodies will cause the blood to agglutinate if the type you added
doesn’t match the type of the blood you are testing.
• For example, if you add type B red blood cells to type A blood, it will
agglutinate.
• So, if you add a known blood type to a sample and it doesn’t
agglutinate-you know the blood types are the same.
DETERMINE GENETIC PROBABILITIES USING BLOOD
TYPES
• Punnet Squares: A parent passes on one of two genes for blood type
to the offspring. One of two genes is also passed on for the Rh factor.
• In order to be recessive in type or Rh, BOTH genes must be recessive.
• Using a Punnet square can determine if a blood type is possible in an
offspring.
• Genotypes:
• Heterozygous-the genes are different (one dominant and one recessive)
• Homozygous-the genes are the same (either both are dominant or both are
recessive)
DETERMINE GENETIC PROBABILITIES USING BLOOD
TYPES
• If a child’s blood type is AB (IAIB), the mother’s type is AB (IAIB) and the
father’s type is O (ii), could the “father” be the genetic father?
IA
i
i
IB
GENETIC PROBABILITIES
• Typical blood typing distribution in the United States.
• www.bloodbook.com/world-abo.html
Blood Type
Percentage
A
40%
B
11%
AB
4%
O
45%
Rh+
85%
Rh-
15%