Blood is made up of red blood cells, white blood cells, platelets, and plasma. Markers called antigens are found on the surface of red blood cells, and differences in these markers classify various ...

Blood – everyone's got it. In fact, an adult who weighs between 150 and 180 pounds has around 1.2 to 1.5 gallons of blood in their body. This makes up approximately 10% of an adult’s weight. Blood ...

A person's blood type is determined by "the presence or absence of certain antigens – substances that can trigger an immune response if they are foreign to the body," according to American Red Cross.