Separation of blood Living portion of blood is Erythrocytes red blood cellsRBCs Leukocytes white blood cells Platelets Liquid part of the blood with no cells in it is called the plasma ID: 912825
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Slide1
Chapter 11; Blood
Slide2Serology; the study of bodily fluids
Slide3Separation of bloodLiving portion of blood is:Erythrocytes (red blood cells…RBCs)Leukocytes (white blood cells)Platelets
Liquid part of the blood with no cells in it is called the
plasma.
(Mostly water with salts, ions, proteins.)
Slide4Slide5BLOOD TRANSFUSIONS were not working!
OUTLAWED IN MOST COUNTRIES IN EARLY 1900’S
Slide6ABO Blood Typing (Karl Landsteiner – 1901)A classification of blood: A, B, AB, O
Rhesus monkey factor (Rh) discovered in 1940.
If you have it, you’re Rh+ and if you don’t you’re Rh-
Slide7Theoretically, no two people have the same combination of blood factors and it should be possible to individualize evidence using blood, but in reality this is not the case. Testing for every factor on RBCs in not practical, and many factors break down as blood dries and ages.Blood is still important in forensics because testing can be done on both whole blood and dried bloodstains quickly and inexpensively.
Slide8Antigens and antibodies
Slide9Each antibody binds to a specific antigen; an interaction similar to a lock and key.
The antibody destroys
the
antigen
Slide10Slide11AGGLUTINATION
THE CLUMPING
TOGETHER
OF RED BLOOD
CELLS
Slide12Lattes slide method
Uses
antibody-antigen
reactions
to test for
blood types
Slide13Varies by country, ethnic group, etc.
Slide14Slide15Blood typing can be used to: -show that two samples had different origins (exclude a suspect) -determine the probability of an individual having a particular blood type
Slide16What is the probability that an American has type AB- blood?
4/100 x 15/100 = 60/10,000 or 0.6%
Slide17Blood Tests
Determines whether a substance is blood or
not, but does NOT distinguish between human and animal blood.
Hemastix
test
Slide18LUMINOL TEST LUMINESCES WITH BLOOD OR SEMEN
Slide19PRECIPITIN TEST
Determines if blood is human
An animal (mammal) is injected with sample. If human, animals produce antibodies.
Slide20Non-mammals
Oval red blood cells with a visible nucleus
Slide21MammalsCircular red-blood cellsNo nucleus
Slide22Secretors
80 % of
population
Blood type antigens are secreted in bodily
fluids (saliva, semen, perspiration,
gastric and vaginal secretions)
Slide23Blood
enzymes
Proteins that regulate chemical reactions
Slide24Iso-enzymesProtein components into which enzymes can be separated
(1) PGM – an enzyme that has 10
variations
(2) importance- allows forensic scientists to reduce the number
of
possible sources
Slide25BLOOD SPATTER
Slide26SIZE AND SHAPE OF DROPS
ARE AFFECTED BY:
HEIGHT OF FALL
ANGLE OF IMPACT
SURFACE ON WHICH THE DROPS LAND
Slide27Shape is determined by the impact angle
Slide28Determination of Impact Angle
Measure the length
and width
of the stain
Slide29Divide the width by the length to get arc sine of the impact angle Width / Length = arc sine of impact angleEx: width = 2.4 cm length = 3.1 cmRatio of width/length = 2.4 cm / 3.1 cm =
.77419
Slide30Use your calculator to get the impact angleEnter: “sin -1 (.77419)”
Answer:
50.7 degrees
50.7
Slide31Blood spatter labs
1. Height of
drops
vs. drop size
2. Angle of drop vs.
drop
shape
3. Surface texture
vs.
drop
size and
shape
Slide32The Nobel Prize in Physiology or Medicine – Educational(Blood type simulation)
Slide33American Justice; Jeffrey MacDonald