Blood Groups and Blood Types

  Table of four blood group 


The differences in human blood are due to the presence or absence of certain protein molecules called antigens and antibodies. 


The surfaces of erythrocytes contain a genetically determined lipids. These antigens, called agglutinogens, occur in characteristic combinations. Based on the presence or absence of various antigens, blood is categorized into different blood groups. Within a given blood group, there are at least 24 blood groups and more than 100 antigens that can be detected on the surface of red blood cells. Here we discuss two major blood groups. ABO and Rh. Other blood groups include the Lewis, Kell, Kidd, and Duffy systems. The incidence of ABO and Rh blood types varies among different population groups.


The antigens are located on the surface of the red blood cells and the antibodies are in the blood plasma. The ABO blood group is based on two antigens called A and B. People who are RBCs display only antigen A has type A blood. Those who have only antigen B are type B. Individuals who have both A and B antigens are type AB and those who have neither antigen A nor B are type O.  


Blood plasma usually contains antibodies called agglutinins. If your blood type is A, you have A antigens on your red blood cells and you have anti-B antibodies in your blood plasma. People with type AB blood do not have anti-A or anti-B antibodies in their blood plasma and they are called universal recipients and can receive blood from donors of all four blood types. On the other hand, people with type O blood have neither A or B antigens on their RBCs and called universal donors because they donate blood to all four ABO blood types. Type O persons can only receive type O blood.


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