Blood types were discovered In 1909 by scientist from Australia named Karl Landsteiner who discovered two distinct blood molecules on two different blood samples. He named one a and one b and if the blood cell have both it’s ab and has none its o.  If your blood is lacking the rh antigen than its rh neg, and an antigen is a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies defined by google. If the blood cells have the antigen than it’s rh positive. An antigen is something in our blood that has our immune system create antibody to use like soldiers when the immune system identifies a threat to the body. The antigen is the Rh and if you don’t have the antigen than you lack the antibody’s.  Antibodies,also called immunoglobulins and gammaglobulins are produced by white blood cells. Antibodies are Y-shaped proteins that respond to a specific antigen (bacteria, virus or toxin). When an antibody binds to a toxin it becomes an antitoxin. Most blood banks can store freshly donated blood for about six weeks then it would be considered old or outdated and disposed of. There are studies that show if blood is transferred after two to three weeks they can cause adverse effects. if you look at blood types with the naked eye than they all look the same but if you were to look at it under a microscope it can clearly be shown that they are different blood sample by the fact that the different red blood cells have different things on them which are antigens. When people see negative and positive in blood types they wonder what it is. It is an antigen known as the Rhesus factor. If you have the antigen you are Rh positive if you lack the antigen you are Rh negative, and about 85% of the population is Rh positive. Osmosis is a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane.Research Says that the human body’s blood is about 7% blood and most adult body’s way 150 to 180 pounds and will contain 1.25 gallons of blood. Red blood cells, white blood cells, And platelets make up 45% of the blood tissue with plasma making up the remaining 55% of the liquid part of the blood.This is the most common transfusion reaction. Hemolytic transfusion reactions can cause the most serious problems, but these are rare. These reactions can occur when your ABO or Rh blood type and that of the transfused blood do not match. If this happens, your immune system attacks the transfused red blood cells.