students will investigate the characteristics of blood blood testing and bloodstain analysis n.
Skip this Video
Loading SlideShow in 5 Seconds..
Unit 6 serology PowerPoint Presentation
Download Presentation
Unit 6 serology

Unit 6 serology

156 Views Download Presentation
Download Presentation

Unit 6 serology

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Students will investigate the characteristics of blood, blood testing, and bloodstain analysis. Unit 6 serology

  2. Erythrocytes Leukocytes Thrombocytes Plasma Antigen RBC WBC Rh Factor Bloodstain Pattern Analysis Surface Tension Low-velocity impact splatter (LVIS) Medium-velocity impact splatter (MVIS) High-velocity impact splatter (HVIS) Drip pattern Cast off pattern Swipe/smear pattern Spurt pattern Expirated pattern Agglutinate (verb) Luminol Blue Star Hydrogen peroxide Kastle-Meyer Passive spatter Transfer spatter Projected spatter Vocabulary

  3. (ERYTHROCYTES, LEUKOCYTES, THROMBOCYTES, AND PLASMA) Solid portion of the blood A. Erythrocytes 1. Red blood cells (RBC). 2. Contain hemoglobin that transports the oxygen and carbon dioxide. 3. Concave in structure. 4. Approximately 30 trillion in the blood. IDENTIFY THE Components AND PHYSICAL PROPERTIES OF BLOOD

  4. B. Leukocytes 1. White blood cells (WBC). 2. Provide immunity for the body and produce antibodies. 3. There are 5 types of white blood cells. 4. Approximately 430 billion in the blood. IDENTIFY THE COMPONETS AND PHYSICAL PROPERTIES OF BLOOD

  5. C. Thrombocytes 1. Platelets (pieces of larger cells). 2. Responsible of starting the clotting process by making fibrin to form a clot. IDENTIFY THE COMPONETS AND PHYSICAL PROPERTIES OF BLOOD

  6. Liquid portion of the blood A. Plasma 1. Fluid portion of the blood that carries the RBC, WBC, and platelets. 2. 55% of blood is the plasma. 3. Made up of 90% water and 10% metabolites (salt, ions, and proteins). IDENTIFY THE COMPONETS AND PHYSICAL PROPERTIES OF BLOOD

  7. ABO blood classification system A. Antigens 1. Proteins found on the surface of every RBC. 2. There are over 100 different antigens in the human blood. 3. Two of the antigens, labeled as A and B, are the ones used on the RBC surface to determine blood type. ANTIGENS AND ANTIBODIES THAT DETERMINE ABO BLOOD TYPES AND THE Rh FACTOR

  8. If antigen A is present a person is A blood type. • If antigen B is present a person is B blood type. • If both antigens A & B are present a person is AB blood type. • If neither antigens A & B are present a person is O blood type. ANTIGENS AND ANTIBODIES THAT DETERMINE ABO BLOOD TYPES AND THE Rh FACTOR

  9. Antibodies • Manufactures by some of the WBC and found in the blood serum. • Function is to attack any invader (antigen) that enters the bloodstream that does not belong in your system. • A person has antibodies again antigens that are not found on the surface of their own RBC. • Rh Factor (Rhesus factor) • Antigen found on the surface of a RBC. • If a person has the Rh antigen they are Rh positive (Rh+). • If a person does not have the Rh antigen they are Rh negative (Rh-). ANTIGENS AND ANTIBODIES THAT DETERMINE ABO BLOOD TYPES AND THE Rh FACTOR

  10. Punnet Squares: A parent passes on one of two genes for blood type to the offspring. One of two genes is also passed on for the Rh factor. In order to be recessive in type or Rh, BOTH genes must be recessive. Using a Punnet square can determine if a blood type is possible in an offspring. This is useful in many ways, one of the most common being paternity. Determine genetic probabilities using blood types

  11. If a child’s blood type is AB+, the mother’s type is AB+ and the father’s type is O-, could the “father” be the genetic father? Determine genetic probabilities using blood types A B O O

  12. Typical blood typing distribution in the United States. Genetic Probabilities

  13. Blood VolumeOn average, accounts for 8 % of total body weight 5 to 6 liters of blood for males 4 to 5 liters of blood for females A 40 percent blood volume loss, internally or/and externally, is required to produce irreversible shock (death). A blood loss of 1.5 liters, internally or externally, is required to cause incapacitation. Properties of blood

  14. Blood typing can be done on people who are called “secretors” 80% of the population are secretors. A secretor is a person who has the gene to secrete blood type substances (A, B & H)in a soluble glycoprotein form in their body fluids, like saliva, tears, gastric juice, etc. The “A” and “B” substances are derived from the “H” substance Blood Typing Using Saliva

  15. If cells do not clump, the person is a secretor If the cells clump (agglutination), the person is a non-secretor Lectin is a plant substance that reacts with blood group substances The lectin will indicate if an H substance is present in the blood (an H substance is the A or B) Blood Typing Using saliva

  16. If H group is present, then anit-A serum and anti-B serum can be added to determine blood group Blood typing using saliva

  17. Before blood can be used as evidence, it must first be confirmed to be blood. Test 1: Presumptive Blood test. This test shows the presence of hemoglobin. It is not human specific. “Every contact leaves a trace.” Blood evidence is extremely important in forensics. It can be used to determine the nature of the crime, blood types, DNA, recreate a crime scene, etc. Blood detection labs

  18. However, running blood tests and DNA tests is very time consuming and expensive. If a sample is sent to a lab for processing, it is best to know if the sample is most likely blood or not. A presumptive blood test “presumes” a substance is blood if it reacts to chemicals in a particular way. The most common presumptive test that is run is the Kastle-Meyer Test . Presumptive blood Test

  19. Kastle-Meyer is quick, inexpensive, easy and does not compromise the integrity of the sample, like DNA. It is very sensitive, 1:10,000. One drop of blood diluted 10,000 times with water can still be detected. It does not distinguish between human and animal blood. It detects the iron in hemoglobin, so other products with iron could also give a positive result. Kastle-meyer test

  20. Products used: Alcohol (cleans sample and exposes more hemoglobin), phenolphthalein (changes color with oxidation – tells you if the test is bad and you need to redo it), hydrogen peroxide (releases extra oxygen, causes the pink color if oxygen is released from the hemoglobin)

  21. Test 2: Luminol Test. This test shows where blood has been present but wiped away. It can also react to a number of substances such as copper or copper-containing alloys, and certain bleaches; and, as a result, if a crime scene is thoroughly cleaned with a bleach solution or horseradish, residual cleaner will cause the entire crime scene to produce the typical blue glow, effectively camouflaging any organic evidence, such as blood. Luminol reacts with fecal matter, causing the same glow as if it were blood. Blood detection labs

  22. Surface TensionThe elastic like property of the surface of the liquid that makes it tend to contract,caused by the forces of attraction between the molecules of the liquid.The cohesive forces tend to resist penetration and separation.

  23. Bloodstain Pattern Analysis:is the examination of the shapes, locations, and distribution patterns of bloodstains, in order to provide an interpretation of the physical events which gave rise to their origin. Based on the premise that all bloodstains and bloodstain patternsare characteristic of the forces that have created them. blood spatter FBI website

  24. The determinations made from bloodstain patterns at the scene or from the clothingof principals in a case can be used to: Confirm or refute assumptions concerning events and their sequence:Position of victim. (standing, sitting, lying)Evidence of a struggle. (blood smears, blood trails) n Confirm or refute statements made by principals in the case:Are stain patterns on a suspects clothing consistent with his reported actions?Are stain patterns on a victim or at a scene consistent with accounts given by witnesses or the suspect? FBI website

  25. At a crime scene the blood spatter patterns are photographed before the blood is collected so that the suspects account can be proved or disproven. The photographs will allow for an interpretation and reconstruction of what happened. • A. Size of blood splatter • 1. Recorded with micro scales visible in photographs. • 2. The smaller the drop the faster the movement of the blood. Blood Spatter

  26. B. Shape of blood spatter 1. Recorded with micro scales visible in photographs. 2. Shape of the mark where it lands reveals the direction in which the drop was traveling and the amount of force it was projected with. C. Directionality of blood spatter 1. The pattern that indicated the direction the blood was traveling when it hit the target surface. 2. Established from the geometric shape of the bloodstain. Blood Spatter

  27. Velocity is the speed at which something travels with a direction. • A. Low-velocity impact spatter (LVIS) • 1. Caused by low-speed impact or force to a blood source. • 2. Velocity may be up to 5 feet per second or 1.5 meters per second. • 3. Drop size is larger than 3 millimeters. Blood spatter

  28. B. Medium-velocity impact spatter (MVIS) • 1. Cause by medium-speed impact or force to a blood source. • a. Blunt force trauma, beating or a stabbing. • 2. Velocity is about 25 feet per second or 1.5-7.5 meters per second. • 3. Drop size or stain of 1-3 millimeters. Blood SPATTER

  29. C. High-velocity impact spatter (HVIS) • 1. Caused by high-speed impact or force to a blood source. • a. Gunshot, explosive devices, a cough or sneeze. • 2. Velocity may be 100 feet per second or 30 meters per second. • 3. Drop size is a mist like appearance forming drops <1 millimeter. Blood spatter

  30. Passive Bloodstains are drops created or formed by the force of gravity acting alone. Drops, drip patterns, pools, clots Drip pattern: A blood stain pattern that results from blood dripping into blood. Blood Spatter Patterns: Passive

  31. A transfer bloodstain is created when a wet, bloody surface comes in contact with a secondary surface. Contact bleeding Swipe or smear Wipe smudge Blood Spatter Patterns: Transfer

  32. 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) Cast-off Arterial spurt Expirated Blood Stain Patterns: Projected

  33. A. Drip pattern: A blood stain pattern that results from blood dripping into blood. • B. Cast-off pattern: A blood stain pattern created when blood is released or thrown from a moving a blood bearing object. • C. Transfer or Contact pattern: A blood stain pattern created when a wet, bloody surface comes in contact with a second surface. • Swipe pattern: The transfer of blood from a moving source into an unstained surface; the direction of travel may be determined by the feathered edges. • Spurt pattern: artierial spurts, appear as lines of blood • Expirated pattern: Blood that is blown out of the nose, mouth, or a wound as a result of air flow, which is the propelling force. Blood spatter patterns Summary

  34. What type of blood spatter pattern?

  35. IN the Forensics book, pages 231-232, there are 35 blood spatter terms. Create flashcards for each term. For the terms which describe how blood spatter looks, create a picture image of what it looks like using water color paints- so your flashcards for the following terms will have a word, a definition and a painted picture example Blood Spatter Vocab Cards

  36. The following terms need to have a painted picture: arterial spurting, bloodstain, cast-off pattern, contact stain, drip pattern, expirated blood, flow pattern, HVIS, impact pattern, LVIS, MVIS, misting, parent drop, passive drip, satellite spatter, spatter, spine, swipe pattern, transfer pattern, void, wipe pattern. For HVIS, MVIS, LVIS, simple put a “drop” mark with the brush that is the right size in diameter. Blood spatter vocab cards

  37. When a droplet of blood strikes a surface perpendicular (90 degrees) the resulting bloodstain will be circular.That being the length and width of the stain will be equal. Blood that strikes a surface at an angle less than 90 degrees will be elongated or have a tear drop shape.Directionality is usually obvious as the pointed end of the bloodstain ( tail ) will alwayspoint in the direction of travel. Directionality of blood spatter

  38. ANGLE of IMPACTis the acute angle formed between the direction of the blood dropand the plane of the surface it strikes iMpact Angle Determination

  39. By utilizing trigonometric functions its possible to determine the impact angle for any given blood droplet. SIN 0 = opp (a) hyp (c)

  40. SIN < = Width (a) 1.5cm Length (c) 3.0cm Width (a) 1.5cm = SIN < Length (c) 3.0cm 0.5 = SIN < < = 30 degrees

  41. Complete the assignment “Angle of Impact” Determining Angle of Impact