CHAPTER 8 Blood and Blood Spatter Objectives 8.1 Explain the composition of blood. 8.2 Describe the functions of blood cells. 8.3 Describe a brief history of the use of blood and blood-spatter analysis in forensics. 8.4 Describe how to determine the blood type of a sample of blood. 8.5 Describe how to screen for the presence of human blood. 8.6 Calculate the probability of certain blood types within a population. 8.7 Conduct a blood-spatter analysis. 8.8 Examine stab wounds and describe the nature of the weapon. 8.9 Use blood-spatter evidence to recreate the events at a crime scene. Chapter 8 Reading Guide Define all key vocabulary terms listed below: 1. Agglutination 2. Antibodies 3. Antigen-antibody response 4. Antigens 5. Cell-surface proteins 6. Lines of convergence 7. Point of origin 8. Red blood cells 9. Satellite drop of blood 10. White blood cells Introduction 1. Explain how blood typing can provide class evidence. 2. Explain how white blood cells can provide individual evidence. 3. How can blood-spatter evidence be used at a crime scene? What can blood-spatter evidence indicate? Blood History 1. Study Figure 8-1 A Chronological history of the study of blood. You are responsible for knowing the following date, who, contribution: a. 1901 b. 1902 c. 1922 d. 1940 e. 1959 Composition of Blood 1. Name the three types of cells that make up blood. 2. Describe the structure and function of plasma and the relationship between plasma and cells of the blood. 3. Draw Figure 8-2 Pie chart showing the distribution of the various components that make up the blood. Rank the components from most common component in the blood to least common. Blood Cells 1. Describe the function of red blood cells. 2. Describe the structure and function of hemoglobin. 3. Describe the function of white blood cells. 4. Describe the function of platelets. 5. Explain how our immune system works. 6. Explain the role of antibodies. History of DNA Profiling 1. Explain the history of DNA profiling. 2. Draw Figure 8-4 The cellular components of blood. (Cells not drawn to scale.) Blood Typing 1. Explain the pros and cons of blood typing in comparison to DNA profiling. Discovery of Blood Types 1. Describe Karl Landsteiner’s discoveries regarding: a. Mixing blood b. Presence of absence of proteins c. A & B proteins and Rh factor d. Cell-surface proteins 2. What is the purpose of an antibody reaction test? A and B Proteins 1. Draw and describe the significance of Figure 8-5. A diagrammatic representation of the cellsurface proteins for the different human ABO blood types. 2. List the U.S. Population Percentages for Type O, A, B, and AB. 3. Review the video “What are Blood Types?”: https://www.youtube.com/watch?v=ttjn1jVACk8 4. For each blood type indicate: a. Antibodies b. Antigens c. Can Donate to d. Can Receive from 5. Practice blood typing Punnett squares Rh Factor 1. Describe Alexander Weiner’s work with Rhesus monkeys and the Rh factor. 2. Describe the presence of Rh in the human population. 3. Explain how Rh relates to positive (+) and negative (-) blood type. Naming of Blood Types 1. What is a person’s blood types based on? 2. Why did the earliest blood transfusions result in death? Antibodies 1. Describe the structure and function of antibodies. 2. Draw Figure 8-7 The general structure of an antibody. 3. Draw Figure 8-8. The shape of the antibody fits the bonding site on the foreign protein or antigen. Antigen-Antibody Response 1. Describe what happens during the antigen-antibody response. 2. Describe the two ways in which the body responds to the presence of an invader. Agglutination 1. Explain how what happens during agglutination. 2. How can agglutination result in death. 3. Draw Figure 8-9. An antibody reaction to surface proteins on red blood cells causes agglutination, or clumping, of the cells. Blood Typing Tests 1. Describe the three tests that are performed to identify blood type. 2. Draw and describe Figure 8-10. Additional Blood Proteins and Probability 1. Draw Figure 8-11 A summary of the population percentages having different blood proteins and enzymes in the United States. 2. Identify the 6 additional enzymes that play a role in identification. Probability and Blood Types 1. Calculate: what percentage of the population would have ______ blood? a. Ab. A+ c. Bd. B+ e. AB+ f. AB- g. O+ h. OBlood Spatter 1. Explain what constitutes a blood-spatter pattern. 2. Explain the usefulness of blood-spatter pattern. History of Blood-Spatter Analysis 1. Describe the significance of 1894. 2. Describe the significance of 1939. 3. Describe the significance of 1955. 4. Describe the significance of 1971. 5. Describe the role of blood-spatter evidence today. Blood-Spatter Analysis 1. Explain what information can be gained from blood-spatter patterns. 2. Describe the forces of gravity, cohesion, adhesion and surface tension that act on blood. 3. Describe the appearance of a drop of blood that has fallen on a flat surface. 4. Define satellites. 5. List and describe the six blood spatter patterns classified by Dr. John Glaister. 6. Explain how the size and shape of droplets help identify the direction from which the blood originated. 7. Explain how spatter patterns can help the investigator determine the type of wound. 8. Define point of origin. Examination of Directionality of Blood 1. Explain how the shape of an individual drop of blood provides clues to the direction from where the blood originated. Explain the impact of cohesion, adhesion, surface tension, and momentum. 2. Draw and describe Figure 8-18. Patterns of cast-off blood. 3. Draw and describe Figure 8-19 Satellite drops. Lines of Convergence 1. Explain the concept of lines of convergence. 2. Draw and describe Figure 8-20. Lines of convergence. Blood Spatter Types 1. Draw Figure 8-21 Table of blood-spatter parameters. Crime-Scene Investigation of Blood 1. Describe the composition of luminol and how luminol can be used to detect blood when the crime scene has been “cleaned”. 2. Describe, in detail, the three steps used in processing a bloodstain. Case Studies 1. Summarize the Ludwig Tessnow (1901). 2. Summarize the Thomas Zeigler (1975). 3. Summarize the Graham Backhouse (1985). .