Antigens=a substance that causes the immun system to produce antibodies which will kill or neutralize the antigens recognized as foreign and potentially hurmful invader.
Are two main systems of antigens: ABO and Rh systems.
ABO System:
1.Group A : 40% of population,red blood cells have A agglutinogens and the plasma contains anti B antibodies.
2.Group B: 10% of the population,red blood cells have B antigen and plasma contain anti A.
3.Group AB: 5% of the population,red blood cellshave both agglutinogens A+B,the plasma does not contain aglutinins.
4.Group O: 45% of population,red blood cells have no agglutinogens but the plasma contain both agglutinins Anti A+Anti B.
Rh System:
People are classified according to the presence or absence of Rhesus antigens (most common type D) into:
-Rh + (with D antigen) 85% of population.
-Rh - (without D antigen) 15% population.
Importance of Blood Groups:
1)Medicolegam importance: Disputed parenthood.Regarding blood groups inheritance 2 antigens are inhirited from both father and mother.This antigens determine the group.The A+B antigens are dominant while the O one is recessive.
2)Blood Transfusion: If transfused blood is incompatible usually the donor red blood cells agglutinated by recipient plasma as the donor's sterum is diluted in recipient blood.
-Group O is the universal donor (no agglutinogens)
-Group AB is the universal recipient (no agglutinins).
3)Importance of Rh Factor: The disease occurs of an Rh - (negative) mother carries an Rh + (positive) foetus,small amounts of foetal blood leak into the maternal circulation at the time of delivery,thus the mother will produce Anti D agglutinins.
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