Blood is a red, sticky fluid. The watery part is called plasma. Several kinds of cells are suspended in the plasma: red blood cells, white blood cells and platelets. Many chemicals are also suspended or dissolved in the plasma, including proteins, sugars, fats, salts, enzymes and gases. Each person's blood has certain inherited characteristics that distinguish it from he blood of other people. But only recently have scientists developed the ability to identify most of these characteristics. Until the 1980's, blood was primarily differentiated according to the presence of three substances that are on the outside of red blood cells called antigens. These are the A, B, and D antigens. The presence or absence of A and B antigens on the the blood determines a persons blood type. If the A antigen is present, the person has A type blood. If the B antigen is present, he has B type blood. If both antigens are present, the blood type is AB. If no antigens are present the person has O type blood. The other important blood antigen is the Rh factor, or D antigen. If one has the D antigen, the person is Rh positive. If he lacks it, he is Rh negative. In order to type a person's blood, antibodies (called agglutinins) made to the antigen are added to the drop of blood. If clumping occurs, then the blood type is known.
|anti-A agglutinin + blood
|anti-B agglutinin + blood
Procedure: Case 96-3337
(Note: because of blood-borne pathogens, you will be working with simulated, not real blood) Sign and date the label on the evidence bags.