Chapter 8: Blood and Spatter 194-211 I say “blood” What Say You? Forensic Science: Fundamentals & Investigations, Chapter 8

Chapter 8: Blood and Blood Spatter What is Blood? Composition of Blood How much is enough? Blood is a primarily a transport system for water, nutrients, and oxygen to all the cells in the body and disposing of wastes like carbon dioxide . It also transports hormones, enzymes, vitamins and minerals (cell nourishment). It regulates certain body functions. Humans could not live without blood! It carries everything we need to every cell in our body, but it also transports wastes to the proper places for disposal. Waste gasses like CO2 are delivered where? (to your lungs) then what do you do (exhale) and what is the result (waste gases are eliminated). Other wastes are filtered from the blood in kidney’s where they are dissolved in (water) and eliminated as (urine).Toxins in blood are eliminated by the liver and foreign substances are identified and destroyed through the action of circulation…again a function of your blood! Did you know that your blood not only is a transportation tool but a communication device too!! The movement of hormones in the blood enables one organ to control the function of another even though the 2 organs might be located pretty far apart from one another. The immune system needs white blood cells to ID and destroy pathogens. (foreign invaders that threaten to make you sick or worse!) Humans have about 5.5 Liters or 6 Quarts of Blood and our hearts beat 300 liters per minute! Our circulatory systems are like the Indy 500 or races at MonteCarlo! Forensic Science: Fundamentals & Investigations, Chapter 8

Whole Blood…. Whole blood carries cells and plasma—the fluid with hormones, clotting factors, and nutrients. Forensic Science: Fundamentals & Investigations, Chapter 8

Blood Cells in Color A kind of painting Shown above respectively: Red blood cells carry oxygen to the body’s cells and carbon dioxide away. White blood cells fight disease and foreign invaders and, alone, contain cell nuclei. Platelets aid in blood clotting and the repair of damaged blood vessels. Forensic Science: Fundamentals & Investigations, Chapter 8

An SEM of Normal Human Blood RBC’s or Ertthrocytes Leukocytes are WBC’s and they have names like Basophil, Eosinophil, lymphocyte, Neutrophil and Moncyte Forensic Science: Fundamentals & Investigations, Chapter 8

An SEM of Platlets and a Clot Forensic Science: Fundamentals & Investigations, Chapter 8

Whole Blood by Fractions This SEM is impressive but let’s look at what’s in the tube too! Forensic Science: Fundamentals & Investigations, Chapter 8

Blood as Evidence Blood typing = class evidence DNA profiling can provide individual evidence. A blood spatter pattern can determine the truthfulness of an account (witness or suspect) origin of the blood, the angle and velocity of impact, and type of weapon used. Our understanding of blood began in ancient times and continues to grow today. In Figure 8-1 on page 196 you will find a time line that is a partial chronological history of the study of blood. 2500 years ago the Egyptians thought blood letting cured disease, the Greeks learned the difference between veins and arteries. From 175 BC until 1935 people learned about the composition of blood, it’s different cells, blood typing and even how to safely transfuse and store blood for later use. By 1900’s Kastle developed a presumptive blood test, and Landsteiner in 1940 discovered Rh protein. When were blood banks established? Why were blood banks established? (1941 for WWII) so that civilians could donate blood for soldiers. 1959 in the Belgian Congo first case of HIV-AIDS is reported and in 1985 the virus causing AIDS was identified. Today, most research goes into screening of blood for new infectious diseases. Blood Typing provides class evidence while DNA can provide individual evidence Spatter patterns corroborates accounts/ truthfulness by suspect or witness 1. Where might you think DNA is found in blood? (White Cells) Red cells are used for typing. How long has DNA analysis been available? Only since 1982 Why is DNA such an important tool for forensic scientists? Because it identifies and individual. Forensic Science: Fundamentals & Investigations, Chapter 8

At the Crime Scene… Dark stains are found Determine if they are blood Even if scene was cleaned up Determine if blood is human Blood type or DNA tests DNA Fingerprint will identify who shed blood Spatter patterns studied tell Direction blood traveled Angle of Impact and Point of Origin Forensic Science: Fundamentals & Investigations, Chapter 8

Wednesday… we will do The Kastle Meyer Presumptive Blood test Blood Typing Activity For Homework TONIGHT Read textbook pages 199-202 Blood Typing Read procedures for lab activities Find for the typo in the text book page 196 and 197 (hint: it has to do with a date) Forensic Science: Fundamentals & Investigations, Chapter 8

Blood Typing—Proteins 42% 12% 3% 43% of the population in the United States (of which 85% is Rh+) Blood typing is quicker and less expensive than DNA profiling. It produces class evidence but can still link a suspect to a crime scene or exclude a suspect. Forensic Science: Fundamentals & Investigations, Chapter 8

Blood Splatter In 1939 the meaning of the splatter pattern was first analyzed. When a wound is inflicted, a blood splatter pattern may be created. It takes a grouping of blood stains to make a blood splatter pattern. The pattern can help to reconstruct the events surrounding a shooting, stabbing, or beating. Forensic Science: Fundamentals & Investigations, Chapter 8

Blood Splatter Analysis Analysis of a splatter pattern can aid in determining the: direction blood traveled. angle of impact. point of origin of the blood. velocity of the blood. manner of death. Forensic Science: Fundamentals & Investigations, Chapter 8