Unit 6 serology Students will investigate the characteristics of blood, blood testing, and bloodstain analysis
Vocabulary • Erythrocytes • Leukocytes • Thrombocytes • Plasma • Antigen • RBC • WBC • Rh Factor • Bloodstain Pattern Analysis • Surface Tension • Agglutinate (verb) • Luminol • Blue Star • Hydrogen peroxide • Kastle-Meyer
Blood spatter vocabulary • Angle of impact • Arterial spurting pattern • Back spatter • Blood spatter analysis • Bloodstain • Cast-off pattern • Contact stain • Direction of flight • Directionality • Directionality angle • Draw-back effect • Drip pattern • Expirated blood • Flight path • Flow pattern • Forward spatter • HVIS • Impact pattern • Impact site • LVIS • MVIS • Misting • Parent drip • Passive drop • Point/area of convergence • Point/area of origin • Projected blood pattern • Satellite spatter • Spatter • Spine • Swipe pattern • Target • Transfer/contact pattern • Void • Wipe pattern
IDENTIFY THE Components AND PHYSICAL PROPERTIES OF BLOOD • (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 COMPONETS AND PHYSICAL PROPERTIES OF BLOOD • 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 • 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 • 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).
ANTIGENS AND ANTIBODIES THAT DETERMINE ABO BLOOD TYPES AND THE Rh FACTOR • 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 • 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 • 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-).
Determine genetic probabilities using blood types • 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 • 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? A B O O
Genetic Probabilities • Typical blood typing distribution in the United States. • www.bloodbook.com/world-abo.html
Objective 3 Blood Spatter
Angle of impact • Arterial spurting pattern • Back spatter • Blood spatter analysis • Bloodstain • Cast-off pattern • Contact stain • Direction of flight • Directionality • Directionality angle • Draw-back effect • Drip pattern • Expirated blood • Flight path • Flow pattern • Forward spatter • HVIS • Impact pattern • Impact site • LVIS • MVIS • Misting • Parent drip • Passive drop • Point/area of convergence • Point/area of origin • Projected blood pattern • Satellite spatter • Spatter • Spine • Swipe pattern • Target • Transfer/contact pattern • Void • Wipe pattern Blood spatter vocabulary
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 patterns are characteristic of the forces that have created them. blood spatter FBI website
The determinations made from bloodstain patterns at the scene or from the clothing of 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
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
B. Shape of blood splatter 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 splatter 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
Velocity is the speed at which something travels with a direction. • A. Low-velocity impact splatter (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
B. Medium-velocity impact splatter (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
C. High-velocity impact splatter (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
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
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
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
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: arterial 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
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
ANGLE of IMPACTis the acute angle formed between the direction of the blood dropand the plane of the surface it strikes Impact Angle Determination
By utilizing trigonometric functions its possible to determine the impact angle for any given blood droplet. • SIN 0 = opp (a) • hyp (c)
SIN < = Width (a) 1.5cm • Length (c) 3.0cm • Width (a) 1.5cm = SIN < • Length (c) 3.0cm • 0.5 = SIN < • < = 30 degrees
The common point, on a 2 dimensional surface, over which the directionality of several bloodstains can be retraced. • Once the directionality of a group of stains has been determined, it's possible to determine a two dimensional point or area for the group of stains. POINT OF CONVERGENCE AND ORIGIN DETERMINATION