Human blood is grouped into four different types. These four different types are : A, B, AB, and O. As you might guess, AB is a combination of, well, A and B. Each letter refers to a kind of antigen (protein) on the surface of the red blood cells. Red blood cells and other formed elements only make up about 45% of blood, the other 55% is this watery, sticky substance called plasma. For example, a person with …showed first 75 words of 408 total…

…showed last 75 words of 408 total…categories... however! There is one type of blood they can not receive. Let's not forget about the Rh factor. Depending upon whether they are Rh+ or Rh-, they can only take blood from someone who has the same Rh antigen as themselves, otherwise the whole antibody illness issue kicks in. Only 4% of the world population has type AB blood, and of that 4%, .7% has type AB- blood. It is very rare and you can see why!