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Serology

Serology. Chapter 12. Serology. It is the study of body fluids Blood Saliva Semen Urine . Functions of Blood. Blood has 3 main functions Transportation Oxygen, carbon dioxide, wastes, nutrients, heat, & hormones Regulation Ph, body temperature, water content Protection

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Serology

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  1. Serology Chapter 12

  2. Serology • It is the study of body fluids • Blood • Saliva • Semen • Urine

  3. Functions of Blood • Blood has 3 main functions • Transportation • Oxygen, carbon dioxide, wastes, nutrients, heat, & hormones • Regulation • Ph, body temperature, water content • Protection • From disease & loss of blood

  4. Characteristics of Blood • Thicker than H2O and flows more slowly • 100.4 F temp • Ph of 7.4 • 8% of body weight • Blood volume • Male- 5-6 liters • Female- 4-5 liters

  5. Components of Blood • Blood consists of • 55% plasma • 45% cells • 99% RBC (red blood cells) • <1% WBC (white blood cells) and platelets

  6. Plasma • 90% H2O • 7% plasma proteins • Albumin- maintain blood osmotic pressure • Globulin- form antigen- antibody complexes • Fibrinogen- for clotting • 3% other substances • Electrolytes, nutrients, hormones, gases, waste products

  7. Formed Elements of Blood • Red blood cells (erythrocytes) • White blood cells (leukocytes) • Platelets (thrombocytes) • Serum

  8. Formation of Blood Cells • Blood cells need to be replaced continuously • Die within hours, days, or weeks • Process is called hematopoiesis • In embryo, occurs in yolk sac, liver, spleen, thymus, lymph nodes, & red bone marrow • In adult- occurs in red bone marrow of sternum, ribs, skull, & pelvis

  9. Red Blood Cells (RBC) • Contains hemoglobin (carries oxygen) • Gives it its red color • Makes up 1/3 of cell’s weight • Is biconcave • Increased sa:vol • Flexible for narrow passages • No nucleus or organelles (no cell division) • In adult • Male- 5.4 million RBC/gttp (drop) • Female- 4.8 million RBC/gttp

  10. White Blood Cells (WBC) • Are leukocytes • Have a nucleus and no hemoglobin • Classified as granular or agranular based on presence of granules in the cytoplasm • Granulocytes- neutrophils, eosinophils, basophils • Agranulocytes- monocytes, lymphocytes

  11. Platelets • Disc shaped • No nucleus present • Normal count • 150000- 400000 gttp/blood • Other blood cell counts • 5 million RBC • 5-10000 WBC

  12. Serum • Is the liquid that separates from the blood when a clot is formed

  13. Immunoassay Techniques • Are available for detecting drugs through antigen-antibody reactions • 2 types of processes • EMIT (enzyme multiplied immunoassay technique) • Antibodies that bind to a specific drug are added to a subject’s urine • RIA (radioimmunoassay) • Uses drugs labeled with radioactive tags

  14. Antigen-Antibody Reactions • When an animal is injected with an antigen, its body will produce a series of different antibodies, all of which are designed to attack some particular site on the antigen of interest • Called polyclonal antibodies • Antibodies designed to combine with a single antigen site can be manufactured • Called monoclonal antibodies

  15. Forensics of Blood • The criminalist must be prepared to answer the following questions when examining dried blood • Is it blood? • From what species did the blood originate? • If the blood is of human origin, how closely can it be associated to a particular individual • Detection of blood is best made by means of a preliminary color test

  16. Presumptive Tests for Blood Determination • 3 tests • Kastle-Meyer color test • Is a mixture of phenolphthalein and hydrogen peroxide • Hemoglobin of blood will cause a deep pink color if blood is present • Hematest tablet • Reacts with the heme group in blood causing a blue-green color • Luminol test • Reacts with blood to produce light

  17. Human vs. Animal Blood • Once the stain has been characterized as blood, the precipitin test will determine whether the stain is of human or animal origin • Uses antisera normally derived from rabbits that have injected with the blood of a known animal to determine the species origin of a questioned bloodstain • Once the bloodstain has been determined to be of human origin, the blood is typed

  18. The Discovery of Blood Types • Before Landsteiner’s discovery, countless people died from blood transfusions • There was an assumption back then that everybody had the same blood • In 1900, Landsteiner proved that there are four different types of blood based on the presence or absence of specific antigens on the surface of RBC’s • Known as ABO blood group • In 1940, he discovered the Rh factor

  19. Blood Types • RBC surfaces are marked by genetically determined glycoproteins & glycolipids • Agglutinogens or antigens • Distinguishes at least 24 different blood types • Most common= ABO & RH

  20. ABO Blood Groups • Based on 2 glycolipid antigens (A & B) found on the surfaces of RBC • Antigen A only= type A blood • Antigen B only= type B blood • Both antigens= type AB blood • No antigens= type O blood • Plasma contains antibodies or agglutinins to the A or B antigens not found in your blood • Anti- A antibody reacts with antigen A • Anti-B antibody reacts with antigen B

  21. Breakdown of ABO Blood Types • Type A- 42% • Type B- 12% • Type AB- 3% • Type O- 43%

  22. Rh Factor • Antigen was discovered in rhesus monkey • Called Rh antigen or D antigen • People with Rh agglutogens on RBC surface are Rh+ (normal plasma contains no anti-Rh antibodies) • Antibodies develop only in Rh- blood type & only with exposure to the antigen

  23. Breakdown of Rh Blood Type • Rh+- 85% • Rh- - 15% • Of the Rh+ population, 85% are Caucasians, 94% are African Americans, and 99% are Asians

  24. Universal Donors and Recipients • People with type AB blood are called universal recipients • No antibodies present • Can receive blood from anybody • People with type O blood are called universal donors • No antigens present • Can donate blood to anybody

  25. Typing and Cross Matching of Blood • Mixing of incompatible blood causes agglutination (visible clumping) • Formation of antigen- antibody complex that sticks cells together • Not the same as blood clotting • Typing involves testing blood with known antisera that contains antibodies A, B, or Rh+ • Cross matching is to test by mixing donor cells with recipient’s serum • Screening is to test recipient’s serum against known RBC’s having known antigens

  26. ABO vs. DNA • Prior to the advent of DNA typing, bloodstains were linked to a source by ABO bloodtyping • DNA analysis has allowed forensic scientists to associated blood and semen stains to a single individual

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