Bloody Notes
Circulation
• If wound spurts (up to 6 feet!) you hit an artery
– Flows away from heart, and therefore under
pressure
– ex.: carotid, femoral, aorta
• If wound pools (up to 6 feet!) you hit a vein
– Flows toward heart, valves don’t allow backflow
– ex.: jugular
Bloody Facts
• Your body contains 12 pints of blood (think
Ben & Jerry’s)
• Blood pressure:
– Systolic is about 120 (pressure during pump)
– Diastolic is about 70 (heart at rest)
• Daily body blood travel: about 12,000 miles
• Heart beats per year: 35 million
• Average amount pumped during life: 3
supertankers
Blood typing and Punnet squares
• Traits that are controlled by
more than two alleles. Blood
type in humans is controlled
by three alleles (or versions
of traits): A, B, and O
• Examples of blood type
crosses in Punnet squares
Phenotype
Genotype
A
AA or AO
B
BB or BO
AB
AB only
O
OO only
Blood Transfusions
• Blood can only be transferred to a body of a person who's immune
system will "recognize" the blood. A and B are antigens on the blood
that will be recognized. If the antigen is unfamiliar to the body, your
body will attack and destroy the transfused blood as if it were a
hostile invader (which can cause death).
• O is like a blank, it has no antigens. O is called the universal donor
because a person can receive a transfusion from O blood without
having an immune response
• AB is the universal acceptor, because a person with AB blood has
both the A and B antigens already in the body, A and B blood can be
transfused to the person (as well as O) and the body will recognize it
and not attack.
• Blood type allows investigators to eliminate suspects, but not
convict. How come?
• See handout for detailed information
Blood spatter
• What can one tell from size and shape of drops?
– Velocity at which the blood was traveling
– Angle at which blood traveled
• Cast offs: drops distributed from swinging weapon
• See handouts for more detailed information
– Or check out this site (CAUTION, graphic blood images):
www.bloodspatter.com
Blood detection at crime scene
• Investigators can spray Luminol about a
room. When a black light shines on the
surface, cleaned blood reveals itself
Blood Diseases
and disorders
Sickle Cell Anemia:
– Had by one in 72000 Americans,
but one in 500 African Americans
Description: Normal red blood cells
are round like doughnuts, and
they move through small blood tubes
in the body to deliver oxygen. Sickle
red blood cells become hard, sticky and shaped like
sickles used to cut wheat. When these hard and
pointed red cells go through the small blood tube,
they clog the flow and break apart. This can cause
pain, damage and a low blood count, or anemia.
Malaria
• The disease is caused by a protistan
parasite of the genus Plasmodium
• Common in tropics
• Flu-like symptoms first, then coma and
potential death
Cycle of malaria
Hemophilia
• Any of several disorders that impairs the
body from controlling bleeding
• Very rare in females,
what does that tell you?