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Blood and Blood Spatter
Blood
• 3 Types of Cells
– Red Blood Cells
– White Blood Cells
– Platelets
• All contained in plasma
that contains proteins:
–
–
–
–
Antibodies
Hormones
Clotting factors
Nutrients (amino acids,
minerals, etc.)
Blood Cells
• Red Blood Cells
– Hemoglobin in the cell is
iron-containing protein
that transport oxygen to
the tissues of the body
• White Blood Cells
– Fights diseases and
foreign invaders
• Platelets
– Aid in blood clotting and
are involved in repairing
damaged blood vessels
Antibodies
• B-lymphocytes (special
white blood cells)
secrete antibodies
– Helps white blood cells
identify foreign proteins
• Y-shaped proten
molecule that binds to
the shape of an antigen.
– The binding site of the
antibody is located on
the tip of the Y and the
antibody recognizes a
foreign substance as an
invader and attaches to
it.
DNA PROFILING
• Dr. Alec Jeffreys used
white blood cells as a
source of DNA to produce
the first DNA Profile
• DNA profiling or DNA
fingerprinting is widely
accepted in programs
such as The Innocence
Project to help free
inmates who have been
falsely convicted of
crimes.
Blood Splatters
• Passive Fall
– Blood falls directly to floor
at 90-degree angle produces
circular drops
• Arterial spurts
– Typically found on walls or
ceilings causes by the
pumping action of the heart
• Splashes
– Shaped like exclamation
points
– Can help locate the position
of the victim at time of
attack
Blood Splatters
• Smears
– Left by bleeding victims
depositing blood as they
touch something
• Trails
– Left my bleeding victims
trying to move
– Droplets can appear as
round, smeared, or spurts
• Pools
– Form around victim who is
bleeding heavily
Directionality of Blood
• The shape of an individual blood drop provides
clues to the direction of where the blood
originated.
– Circular drop: blood fell straight down
– Elongated: possible to determine direction the blood
was traveling as it struck the surface
– Blood strikes the surface
• Cohesion: force between 2 similar substances
• Adhesion: force between 2 unlike surfaces (ex- blood and
wall)
• Surface tension: elastic characteristic along the outer edge
of liquid caused by attraction of like molecules