Download The Rh factor

Dentistry college
Practical physiology
Lecturer :
Jameela k . Alomary
Blood groups and Rh factor determination
Blood typing is a test that determines a person's blood type .
The test is essential if you need a blood transfusion or are
planning to donate blood . your blood type is determined by
what kind of antigens your red blood cells have on the surface .
The A , B , O blood typing system groups your blood into one
of four categories :



Type A has the A antigen .
Type B has the B antigen .
Type AB has both A and B antigens .
Type O has neither A nor B antigens .
If blood enters your system with antigens that you don’t have .
your body will create anti bodies angainst it .However , some
people can still safely receive blood that isn’t their blood type .
so long as the blood they receive doesn’t have any antigens that
mark it as foreign, their bodies won't attack it .
Notes :
 O : type O individuals can donate blood to anyone (
because their blood has no antigens ) , but can receive
blood only from other type O individual . ( because blood
with any antigens is seen as foreign )
 A : type A individuals can donate to other type A
individuals and type AB individuals type A individuals
can receive blood only from other type A individuals and
type O individuals .
 B : type B individuals can donate blood to other B
individuals and AB individuals . type B individuals can
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Dentistry college
Practical physiology
Lecturer :
Jameela k . Alomary
receive blood only from type B individuals and type O
individuals .
 AB : type AB individuals can give blood only to other AB
individuals , but can receive blood of any type .
The Rh factor
More than 85% of the population has another red cell amtigen
group called the Rh factor , named for Rhesus monkey , in wich
it was first found .
Rh is also known as the D antigen . people with this antigen are
said to be Rh positive . those who lack this protein are said to be
Rh negative ( 15% ) .
 Rh + : people with Rh- positive blood have Rh antigens on
the surface of their red blood cells . people with Rh+ blood
can receive Rh+ or Rh- blood
 Rh - : people with Rh- negative blood do not have Rh
antigens . people with Rh- blood can receive only blood
that is also Rh- .
Blood groups and pregnancy
A blood group test is always done on pregnant women . If the
mother is Rh negative and the unborn baby is Rh positive (
inherited from Rh positive father ) then the mother's immune
system may produce anti- Rh antibodies . these may attack and
destroy the baby's blood cells . This is rarely a problem in a first
prergnancy . However , whithout treatment , this can become
aserious problem in subsequent pregnancies , as the mother's
immune system will be sensitised after the first pregnancy .
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Dentistry college
Practical physiology
Lecturer :
Jameela k . Alomary
The principle :
A drop of blood is mixed with anti- A , anti- B and anti – D sera
and examined for agglutination .
Objective :
To determine the group ABO and Rh factor .
Apparatus and Reagents
Slide method
1- Anti- ABO sera kit .
2- Glass slides .
3- Sticks for mixing .
4- Lancet .
5- Blood sample .
Procedure
1- Divide a glass slide into three areas A, B and D .
2- Add one drop of anti- A, anti-B and anti – D into each
division ( A , B and D ) .
3- Prick a finger with asterile Lancet , and place one drop of
blood in areas A , B and D .
4- Mix them ( blood and serum ) separately and well with
clean match stick .
5- After two minutes observe the area for the evidence of
agglutination of the red cells .
6- Find out the blood groups using the following table .
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Dentistry college
Practical physiology
Lecturer :
Jameela k . Alomary
Anti – A serum
Anti – B serum
Anti – D serum
Blood group
and Rh type
+
+
+
+
-
+
+
+
+
-
+
+
+
+
-
A+
AB+
BAB+
ABO+
O-
Figure (2): Adding of anti-sera
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Dentistry college
Practical physiology
Lecturer :
Jameela k . Alomary
Figure (1) : Blood typing
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