Blood Groups
Anatomy & Physiology/Cardiovascular System
Vocabulary
• Antigen (agglutinogens) = genetically
determined proteins that mark each
person’s blood in a unique way.
• If an antigen other than your own
enters your body, the body recognizes it
as foreign and triggers the immune
system to release antibodies against it.
vocabulary
• Antibodies (agglutinins) = proteins contained in the
blood plasma which identify foreign antigens and alert
the immune system.
• Once identified, antibodies bind to the foreign blood cells
and cause them to clump, a process called agglutination.
Blood transfusion
• When blood vessels are broken, blood loss can lead to
weakness, shock and eventually death.
• Loss of over 30% of a person’s total blood volume can
be fatal unless treated with a whole blood transfusion.
• Whole blood transfusion is also used to treat chronic
health conditions such as anemia or
thrombocytopenia.
• When giving a blood transfusion, it is essential to test
the blood groups of both the donor and recipient.
human Blood
groups
• There are over 30 common
antigens found on human
red blood cells.
• However, the antigens of
the ABO and Rh blood
groups cause the most
severe transfusion
reactions.
ABO Blood Group
• The ABO blood group is based on two antigens:
Antigen A and Antigen B.
•
•
•
•
Type A Blood = Presence of antigen A
Type B Blood = Presence of antigen B
Type AB Blood = Presence of antigens A and B
Type O Blood = Neither antigen A or B
• These antigens are genetically determined.
• Antibodies are formed during infancy to protect the
body against antigens NOT present in your own blood.
ABO blood group
ABO blood group
• During a blood transfusion, only certain types of
donor blood will be successfully transplanted in a
recipient.
• For example: a recipient with type A blood can only
receive a transfusion of type A OR type O blood. If
given type B blood, the anti-B antibodies in the
recipient’s plasma will attack the A antigens causing
agglutination.
• Agglutination causes blood cells to rupture, releasing
hemoglobin into the blood stream which often blocks
kidney tubules and results in kidney failure.
Abo blood group
• Universal Donor: Since
Type O blood does not
contain any antigens,
anyone can receive this
blood.
• Universal Recipient: Since
Type AB blood does not
contain any antibodies, it
can receive any type of
transfusion.
Rh blood group
• Called Rh because one of the eight Rh antigens was
originally identified in Rhesus monkeys.
• Rh+ = blood cells contain Rh antigens
• Rh- = blood cells do not contain Rh antigens, plasma has
the potential to create anti-Rh antibodies.
• If an Rh- recipient receives an Rh+ blood transfusion,
shortly after the transfusion the immune system begins
making anti-Rh antibodies.
• A second transfusion of Rh+ blood will result in
agglutination.
Rh blood and
pregnancy
• Serious medical conditions can result if Rh- women
become pregnant with Rh+ babies.
• The first pregnancy usually results in a healthy baby;
however, during this time the baby’s Rh+ antigens
move through the placenta and trigger the mother’s
immune system to produce anti-Rh antibodies.
• If the mother has a second pregnancy with an Rh+
baby, the mother’s anti-Rh antibodies will attack and
destroy the baby’s blood cells, resulting in brain
damage and possibly death.
Rh blood and
pregnancy
• If detected during the first pregnancy, the mother can
be treated with a medicine called RhoGAM, which
will suppress her immune response.