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Unit 5 Blood

Unit 5 Blood. 5.2 Presumptive Testing. Unknown Stain at a Scene. Questions to be answered: Is it blood? Is it human blood? Whose is it? Determine blood type, alcohol content, drugs present Determine the method(s) in which blood may have been deposited.

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Unit 5 Blood

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  1. Unit 5 Blood 5.2 Presumptive Testing

  2. Unknown Stain at a Scene Questions to be answered: • Is it blood? • Is it human blood? • Whose is it? • Determine blood type, alcohol content, drugs present • Determine the method(s) in which blood may have been deposited Kendall/Hunt Publishing Company

  3. Presumptive Tests forBlood Determination • Kastle-Meyer color test—a mixture of phenolphthalein and hydrogen peroxide; the hemoglobin will cause the formation of a deep pink color if blood is present • Hematest® tablet—reacts with the heme group in blood causing a blue-green color • Luminol test—reaction with blood to produce light Kendall/Hunt Publishing Company

  4. Human vs Animal Blood • Microscopic observation • Precipitin test—blood is injected into a rabbit; antibodies are formed; the rabbit’s blood is extracted as an antiserum; the antiserum is placed on sample blood. The sample will react with human proteins if human blood is present. This test is very sensitive and requires only a small amount of blood. Kendall/Hunt Publishing Company

  5. Animal Blood Larger nucleic red blood cells Frog Blood Kendall/Hunt Publishing Company

  6. Human Blood • Red blood cells are most numerous; 5 to 6 million per mm3 • White blood cells are larger and less numerous; 5 to 10,000 per mm3 • Platelets are tiny, cellular fragments; 350 to 500,00 per mm3 Kendall/Hunt Publishing Company

  7. Blood Typing • Blood type A has antigen A on the surface of the cell and will agglutinate with blood type B. • Blood type B has antigen B on the surface of the cell and will agglutinate with blood type A. • Blood type AB has antigens A and B on the surface of the cells and will not agglutinate with either type A or B blood. • Blood type O has neither antigen A or B and will not agglutinate. Kendall/Hunt Publishing Company

  8. Blood Groups Can Give Blood To Can Get Blood From Antigen Type Antibody A A B A, AB O, A B, AB O , B B B A Neither A nor B AB A and B AB A, B, O, AB Neither A nor B A, B, O, AB O A and B O Kendall/Hunt Publishing Company

  9. Population Distribution of Blood Types in the U.S. Type Percent O 45 A 40 B 11 AB 4 Kendall/Hunt Publishing Company

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