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Blood

Chapter 11. Blood. Serology: study of bodily fluids. 1/12 of body is blood Cells suspended in plasma (55% of blood) Plasma = 90% water, 10% metabolites, waste, salts, ions, proteins. Cells :. Erythrocytes – red blood cells, contain hemoglobin (carries oxygen from lungs to cells)

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Blood

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  1. Chapter 11 Blood

  2. Serology: study of bodily fluids • 1/12 of body is blood • Cells suspended in plasma (55% of blood) • Plasma = 90% water, 10% metabolites, waste, salts, ions, proteins

  3. Cells: • Erythrocytes– red blood cells, contain hemoglobin (carries oxygen from lungs to cells) • Leukocytes – white cells; • produce antibodies • Platelets – start clotting process – form fibrin leaves behind yellow watery fluid - serum

  4. ABO Blood Typing and Rh Factor • Can be done on whole blood and dried blood stains • 80% of population are “secretors” – their blood type antigens (foreign substance that can cause disease – triggers an immune response – antigens bind to specific antibodies) are found in body fluids other than blood

  5. Blood typing continued

  6. Rh Factor – another factor (there are ~100 factors) • “the D antigen” • Rh positive or Rh negative – 85% of population is Rh+ • Rh = Rhesus factor

  7. White blood cells • Produce antibodies to attack antigens that enter your system – ex: snake venom, viruses, someone else’s blood

  8. Blood Types

  9. Blood typing and forensics • Can show that two samples had different origins – can exclude suspects • Distribution of blood types within a population can be used to statistically determine the probability of someone having a particular combination of blood types

  10. Detecting Blood at the Crime Scene

  11. Is it really blood? • Presumptive chemical color tests: may be false positives • Hematest tablet – turns blue in presence of oxygen (hemoglobin – oxygen carrier; give red blood cells their color)

  12. Kastle-Meyer Test • deep pink when added to hydrogen peroxide and blood – • false positives with potatoes and horseradish

  13. Leucomalachite Green –forms color when oxidized (like above tests)

  14. – may be false positives • Luminol test – spray to make old bloodstains glow (chemiluminescence)

  15. Next… is it human or animal blood? • Precipitin test • – uses an rabbit serum (liquid that separates from clotted blood) that contains antibodiesspecific to human antigens • reacts to agglutinate (a reaction where red blood cells clump in response to an antibody) human blood • bloodstains many years old can test positive

  16. Blood Spatter Analysis

  17. Key Terms to describe bloodstains: • Your assignment is to research five of these terms with your group. Explain and give examples of each.

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