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UNIT 6 SEROLOGY
STUDENTS WILL INVESTIGATE THE CHARACTERISTICS OF
BLOOD, BLOOD TESTING, AND BLOODSTAIN ANALYSIS
VOCABULARY
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Erythrocytes
Leukocytes
Thrombocytes
Plasma
Antigen
RBC
WBC
Rh Factor
Bloodstain Pattern
Analysis
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Surface Tension
Agglutinate (verb)
Luminol
Blue Star
Hydrogen peroxide
Kastle-Meyer
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 for 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.
DETERMINE GENETIC PROBABILITIES
USING BLOOD TYPES
• If a child’s blood type is AB (IAIB), the mother’s type
is AB (IAIB) and the father’s type is O (ii), could the
“father” be the genetic father?
IA
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GENETIC PROBABILITIES
• Typical blood typing distribution in the United States.
• www.bloodbook.com/world-abo.html
Blood Type
Percentage
A
40%
B
11%
AB
4%
O
45%
Rh+
85%
Rh-
15%
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
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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
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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 spatter
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 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
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
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
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
• 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.
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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
• Drip pattern: A blood stain pattern that results from blood dripping
into blood.
• Cast-off pattern: A blood stain pattern created when blood is released
or thrown from a moving a blood bearing object.
• 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
What type of blood
spatter pattern?
• 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 always
point in the direction of travel.
Directionality of blood
spatter
• ANGLE of IMPACT is the acute angle formed between
the direction of the blood drop
and 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)
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hyp (c)
• SIN < = Width (a) 1.5cm
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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