Jul 5, 2013
There are 8 main types of blood separated into 4 groups. The groups are A, B, AB, and O. They are grouped together by the presence or absence of an antigen. Antigens are substances within the blood that cause our immune systems to create antibodies. These antibodies kill anything the immune system thinks is a threat.
The specific antigens that create the different blood types are found on the surface of red blood cells and are known as type A and type B. They are separated by the presence of another type of antigen known as rH factor. If this rH antigen is present, blood is considered positive, if absent, negative.
Someone that has type A antigens and rH factor is considered type A+. If someone has both types of antigens and no rH factor would be type AB- blood. If no A or B antigens then it is type O.
All of this matters because of those antibodies your immune system creates. Someone with type A blood will have antibodies for type B, and someone with type B will have antibodies for type A. Type O has antibodies for both A and B. If you were to give type B blood to someone who was type A, their antibodies would attack the type A red blood cells causing very unwanted side effects, including possible death.
The two main types of cells within the blood are red and white. Red blood cells make up nearly 45% of your blood volume. White blood cells make up less than 1%. What is left over is blood plasma at approximately 55% of blood volume.
Red blood cells and most white blood cells are predominantly created within the bone marrow of large bones. White blood cell production is controlled within the immune system.