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SEROLOGY The examination & identification of body fluids 1/12th of our body is made of BLOOD Other fluids studied: Sweat Tears Saliva Semen Vaginal fluids SEROLOGY Blood is: “mixture” of blood cells & plasma. a liquid with dissolved particles AND with very small solid particles suspended within it. Gravity acts on blood pulling it downward. Blood has cohesive forces: keeping it together rather than letting it separate as it falls. this keeps it from flattening out when it lands on a surface. Blood accounts for approximately 8% of total body 5-6 liters for males, 4-5 liters for females Blood loss of 1.5 liters causes incapacitation Blood loss of 40% causes death A droplet of blood contains approximately 0.05mL of blood “Hematocrit” value: the % of packed red blood cells 15-29% = thin, will bleed out; chronic alcoholics 30-48% = normal 49-75% = thick, people in shock; “fight or flight” HISTORY See chart p.196-197 Basically, it goes a long way back and keeps on changing 1) Antony Leeuwenhoek (1659) First to see blood cells with a microscope 2) Karl Landsteiner Discovered 2 proteins on blood cells A&B Gave rise to 3 blood types: A,B,O 3) Percy Oliver Started the blood donor service COMPOSITION OF BLOOD 1) Red blood cells (erythrocytes) (RBC’s) carry oxygen via the hemoglobin molecule Iron in hemoglobin binds with oxygen 2) White blood cells (leukocyes) (WBC’s) fight disease & illness the only blood cell with a nucleus, so this is how we can get DNA from blood 3) Platelets (thrombocytes) aid in clotting & repairing blood vessels All of these components are suspended in PLASMA carries proteins, sugars, antibodies, hormones, etc Blood is made of 45% cells & 55% plasma PLASMA fluid portion of blood CELLS ◦ Erythrocytes = red blood cells; responsible for gas distribution. ◦ Leukocytes = white blood cells; responsible for “cleaning” blood of foreign invaders. Produce antibodies. Contain DNA ◦ Thrombocytes/platelets = are responsible for blood clotting Serum = liquid that separates from the blood when a clot is formed. Kendall/Hunt Publishing Company 6 8% of your total body weight is made up of blood males have 5-6L of blood females have 4-5L of blood 1 drop of blood is approx. 0.03-1.5mL of volume Blood loss of: 1.5L = incapacitation 40% = death “Hematocrit” value: the % of packed red blood cells 15-29% = thin, will bleed out; chronic alcoholics 30-48% = normal 49-75% = thick, people in shock; “fight or flight” Unknown Stain at a Scene Questions to be answered: 1) Is it blood? 2) Is it human blood? 3) Whose is it? Presumptive test for blood determination: Kastle-Meyer color test Hematest® tablet Luminol test Larger nucleic red blood cells in Frog blood Human vs. Animal blood: Microscopic observation Precipitin test Human blood Fish Blood Bird Blood Horse Blood Frog Blood Cat Blood Dog Blood Human Blood Snake Blood HOW IT’S USED FOR EVIDENCE: Class evidence for blood would include blood type. If you can determine the DNA you would have individual evidence. Blood stain patterns are considered circumstantial evidence. Experts could argue many points including direction of travel, height of the perpetrator, whether the body was moved, etc. Collecting Blood Evidence at the Scene: •Collect liquid before coagulation if possible With syringe, place in vial and get refrigerated •Scrape dried blood into vial, envelope Collect material from surrounding area as control •If blood can not be scraped off: Moisten swab and dab at stain until swab is deep red/brown. Place in vial Cut out section of evidence and wrap in paper. Do NOT use plastic bags!! This degrades the blood. Who’s blood is it??? Blood Typing & DNA fingerprinting Who’s Your Daddy??? Remember Punnett squares from Biology??? A women wants to find out if so-and-so is the father of her baby. She wants child support and is convinced that he is the true father. She takes him on TV and wildly denies that she has been with 100 other guys; only ‘him’. The baby has blood type A. Mom has blood type AB and Dad has blood type ‘B’. Can he be the father? Remember that the genotype for blood types can be either homozygous or heterozygous. So, what do you remember? Mom’s genotype is definitely AB. Dad can be homozygous (BB) or he could be heterozygous (BO) for blood type B. Place the genotypes in the Punnett and figure out the possible offspring of this union. Is ‘so-and-so’ the father? Is this conclusive? A B A B B B B O “Genotype” vs. “Phenotype”??? Phenotype: This is the "outward, physical manifestation" of the organism. Genotype: This is the "internally coded, inheritable information" carried by all living organisms. Genotype Phenotype AA or AO = Type A BB or BO = Type B OO = Type O AB = Type AB According to the ABO blood typing system there are four different kinds of blood types: A, B, AB or O Do you know what type you are??? Some of you are “secretors”: blood type can be found in body fluids other than blood 70-80% of population are secretors Blood group A If you belong to the blood group A: you have A antigens on the surface of your red blood cells and B antibodies in your blood plasma. Blood group B If you belong to the blood group B: you have B antigens on the surface of your red blood cells and A antibodies in your blood plasma. Blood Type AB Blood Type O “Rh” comes from the rhesus monkey this blood cell protein was first found on. You either have the protein (+) or you don’t (-) The problem occurs when an Rh – mother is pregnant with an Rh + baby. The mother’s blood detects the + protein and starts producing antibodies against The babies blood. The mother is treated to help prevent the production of antibodies. United States population: Rh + = 85% Rh - = 15% Blood Group AB A B O Antigens Antibodies Can give blood to Can receive blood from Universal Donor: Blood Type distribution in the United States: Type O Universal Receiver: A = 42% Type AB B = 12% AB = 3% O = 43%