1 Chapter12 Blood


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1 Chapter12 Blood

  1. 1. <ul><li>Chapter 12 </li></ul>Forensic Serology (Blood)
  2. 2. Karl Landsteiner <ul><li>In 1901 he discovered that all humans do not have the same blood type </li></ul><ul><li>He discovered the A-B-O blood group system </li></ul><ul><li>This saved millions of lives by preventing mismatched blood transfusions </li></ul><ul><li>Other researchers were able to discover the Rh factor because of his research </li></ul><ul><li>29 years later, they gave Karl a Nobel Prize </li></ul>
  3. 3. Part 1: What is Blood ?
  4. 4. What is Blood ? <ul><li>Various cell types found in a liquid matrix called plasma </li></ul><ul><li>Erythrocytes (RBCs) </li></ul><ul><ul><li>Transport O 2 , CO 2 </li></ul></ul><ul><ul><li>Stay within blood vessels </li></ul></ul><ul><li>Leukocytes (WBCs) </li></ul><ul><ul><li>Fight infection (immune system) </li></ul></ul><ul><ul><li>Can move from blood ve ssels into tissues </li></ul></ul><ul><li>Platelets (Cell fragments) </li></ul><ul><ul><li>Help with clotting </li></ul></ul>
  5. 5. Platelets White Blood Cell Red Blood Cells
  6. 6. Characteristics of Red Blood Cells <ul><li>Red blood cells are biconcave disks. </li></ul><ul><li>In addition to 100s of cell surface proteins, their cell surfaces have a special class of blood factor proteins called Antigens. </li></ul><ul><li>There are at least 15 different antigens, but the most important are the ABO and Rh antigens </li></ul>Role of RBCs <ul><li>Transport inhaled O 2 and remove CO 2 from lungs to all body cells </li></ul><ul><li>When oxygen combines with hemoglobin bright red. </li></ul><ul><li>Deoxygenated blood or blood containing CO 2 is darker. </li></ul><ul><li>RBCs are destroyed after about 120 days </li></ul>
  7. 7. Blood Platelets <ul><li>Blood platelets are fragments of cells </li></ul><ul><li>Repair damaged blood vessels. </li></ul>Leukocytes can squeeze between cells lining walls and attack bacteria and debris. Neutrophils engulf larger particles. Eosnophils moderate allergic reactions. Basophils migrate to damaged tissues and release histamine to promote inflammation. Lymphocytes are the major players in specific immune reactions and some produce antibodies (T cells and B cells) Functions of WBCs
  8. 8. Blood Plasma <ul><li>Plasma is the clear, straw-colored fluid portion of the blood . </li></ul><ul><li>Plasma is mostly water, with a mixture of, amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, and cellular wastes </li></ul>
  9. 9. Hematocrit <ul><li>A blood hematocrit is normally 45% cells and 55% plasma. </li></ul>Hematocrit means the percentage of red blood cells in blood
  10. 10. ABO Blood Group <ul><li>Type A blood has A antigens on red blood cells and anti-B antibodies in the plasma. </li></ul><ul><li>Type B blood has B antigens on red blood cells and anti-A antibodies in the plasma. </li></ul><ul><li>Type AB blood has both A and B antigens, but no antibodies in the plasma. </li></ul><ul><li>Type O blood has neither antigen, but both types of antibodies in the plasma. </li></ul><ul><li>Adverse transfusion reactions are avoided by preventing the mixing of blood that contains matching antigens and antibodies. </li></ul><ul><ul><li>Adverse reactions are due to the agglutination of red blood cells. </li></ul></ul>
  11. 12. Rh Blood Group <ul><li>The Rh factor was named after the rhesus monkey. </li></ul><ul><li>If the Rh factor surface protein is present on red blood cells, the blood is Rh positive; otherwise it is Rh negative. </li></ul><ul><li>There are no corresponding antibodies in the plasma unless a person with Rh-negative blood is transfused with Rh-positive blood; the person will only then develop antibodies for the Rh factor. </li></ul>
  12. 14. Blood Groups and Transfusions Antigens and Antibodies <ul><li>Clumping of red blood cells following transfusion is called agglutination. </li></ul><ul><li>Agglutination is due to the interaction of proteins on the surfaces of red blood cells (antigens) with certain antibodies carried in the plasma. </li></ul><ul><li>Only a few of the antigens on red blood cells produce transfusion reactions. </li></ul><ul><ul><li>These include the ABO group and Rh group. </li></ul></ul>
  13. 15. Agglutination of RBCs
  14. 16. Relative Frequency of Blood Types in Human Populations
  15. 17. Part II : Is it blood?
  16. 18. Questions for a Criminalist: <ul><li>Is it blood? </li></ul><ul><li>Is it human blood? </li></ul><ul><li>If it is human, can it be linked to a suspect / victim and how closely? </li></ul>
  17. 19. Tests to identify human blood <ul><li>Benzidine color test was used for years to identify human blood </li></ul><ul><li>Kastle-Meyer Test When blood, phenolphthalein and hydrogen peroxide are mixed, the hemoglobin in the blood will cause the normally colorless phenolphthalein to a bright pink color </li></ul><ul><li>Hemastix© strips to detect blood in urine. But these strips can be used at a crime scene to detect fresh or dried blood. </li></ul>
  18. 20. Bayer Hemastix©
  19. 21. 4. Luminol <ul><li>Luminol is a chemical that exhibits chemiluminescence, with a striking blue glow, when mixed with an appropriate oxidizing agent. It is a white to slightly yellow crystalline solid that is soluble in water and most polar organic solvents. </li></ul><ul><li>Usually, a solution of hydrogen peroxide (H 2 O 2 ) and a hydroxide in water is used as the activator. </li></ul><ul><li>In the presence of a catalyst such as an iron compound, the hydrogen peroxide is decomposed to form oxygen and water: </li></ul>
  20. 22. What do you see with luminol? It glows a bright blue in the dark, when it comes in contact with blood
  21. 23. Advantages of using Luminol <ul><li>Allows one to detect stains that would not be ordinarily be visible </li></ul><ul><li>Extremely sensitive - can use it in very dilute concentrations </li></ul><ul><li>This allows the CSI to spray large areas with it </li></ul><ul><li>It does not interfere with DNA, so a CSI can collect samples for DNA analysis even after it was sprayed with luminol. </li></ul>
  22. 24. Bloody Footprints that were wiped
  23. 25. 5. Crystal Tests <ul><li>Less sensitive than color tests </li></ul><ul><li>They involve the crystallization of certain components of blood when certain chemicals are added </li></ul><ul><li>Takayama test and Teichman test </li></ul><ul><li>Not used as much by CSI </li></ul>
  24. 26. So we know it’s blood – but is it human? <ul><li>6. The Precipitin Test </li></ul><ul><ul><li>Rabbits injected with human blood </li></ul></ul><ul><ul><li>They make antibodies in their serum </li></ul></ul><ul><ul><li>They are bled and the serum recovered </li></ul></ul><ul><ul><li>The serum is called human antiserum, because it will react to human antigens </li></ul></ul><ul><ul><li>It will cause coagulation when mixed with human blood </li></ul></ul>
  25. 27. Precipitin Test (Human blood) (Human antiserum made in rabbits)
  26. 28. 7. Gel Diffusion Test <ul><li>Antigen (blood) and antibodies (human antiserum from rabbits) are placed in separate wells in a gel. </li></ul><ul><li>They are forced to move towards each other. </li></ul><ul><li>If they bind to each other, they form a single line of precipitate in between the wells </li></ul><ul><li>This is a positive for human blood </li></ul>
  27. 29. 8. DNA TEST <ul><li>DNA testing is the ultimate </li></ul><ul><li>It has made most other tests for determining if the blood is human, obsolete </li></ul>
  28. 30. Part III. Analyzing Bloodstain Patterns
  29. 31. Analyzing Bloodstain Patterns <ul><li>Surface Texture The harder and less porous the a surface, the less spatter results </li></ul><ul><li>Direction of travel The pointed end of a bloodstain always faces the direction of travel </li></ul><ul><li>Impact angle If the strike angle is 90 o then the stain is circular. As the strike angle increases, the stain becomes more and more elongated </li></ul><ul><li>Origin of blood spatter If you draw straight lines through the long axis of several blood stains, the point where the lines converge is the origin of the blood spatter </li></ul>
  30. 35. Types of Blood Stain Patterns <ul><li>Passive </li></ul><ul><li>Projected </li></ul><ul><li>Transfer </li></ul>
  31. 36. <ul><li>Passive Bloodstains </li></ul><ul><li>Passive stains are drops created or formed by the force of gravity acting alone. </li></ul><ul><li>This category can be further subdivided to include: </li></ul><ul><ul><ul><li>Drops </li></ul></ul></ul><ul><ul><ul><li>Drips </li></ul></ul></ul><ul><ul><ul><li>Pools </li></ul></ul></ul>
  32. 37. Passive drops on various surfaces <ul><li>Blood droplets that strike a hard smooth surface, like a piece of glass, will have little or no distortion around the edge. </li></ul><ul><li>Blood droplets that strike a rough surface have a slightly different appearance. They tend to be distorted, scalloped or spined at the edges. </li></ul>
  33. 38. Passive: Dripped Blood patterns created by a volume of blood, from same source to target distance (repeated drops onto same spot.)
  34. 39. <ul><li>Projected Bloodstains </li></ul><ul><li>Projected bloodstains are created when an exposed blood source is subjected to an action or force, greater than the force of gravity. (Internally or Externally produced) </li></ul><ul><li>The size, shape, and number of resulting stains will depend, primarily, on the amount of force utilized to strike the blood source. </li></ul><ul><li>This category can be further subdivided to include: </li></ul><ul><ul><li>Arterial Gush or spurt </li></ul></ul><ul><ul><li>Cast-off stains </li></ul></ul><ul><ul><li>Impact spatter (medium or high velocity) </li></ul></ul>
  35. 40. Arterial gush or spurt <ul><li>Bloodstain pattern (s) resulting from blood exiting the body under pressure from a breached artery. </li></ul>
  36. 41. Cast-off Stains <ul><li>Blood released or thrown from a blood-bearing object in motion (Knives, bludgeons) </li></ul>
  37. 42. Projected blood through a syringe
  38. 43. Impact Spatter <ul><li>Blood stain patterns created when a blood source receives a blow or force resulting in the random dispersion of smaller drops of blood. </li></ul><ul><li>This category can be further subdivided into; </li></ul><ul><ul><li>Low Velocity </li></ul></ul><ul><ul><li>Medium Velocity </li></ul></ul><ul><ul><li>High Velocity </li></ul></ul>
  39. 44. Low Velocity Impact Spatter <ul><li>Gravitational pull up to 5 feet/sec. </li></ul><ul><li>Relatively large stains 4mm in size and greater </li></ul>
  40. 45. Medium Velocity Impact Spatter <ul><li>Force of 5 to 25 feet/sec. </li></ul><ul><li>Preponderant stain size 1 to 4mm in size </li></ul>
  41. 46. High Velocity Impact Spatter Force of 100 feet/sec. and greater Preponderant stain size 1mm in size and smaller Mist like appearance
  42. 47. <ul><li>Transfer Bloodstains </li></ul><ul><li>A transfer bloodstain is created when a wet, bloody surface comes in contact with a secondary surface. </li></ul><ul><li>A recognizable image of all or a portion of the original surface may be observed in the pattern, as in the case of a bloody hand or footwear. </li></ul>