3B-1 Blood.pdf
Transcript of 3B-1 Blood.pdf
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Learning Objectives
Explain blood biochemistry and blood typ
Conduct blood spatter analysis to find source of blood and reconstruct past ev
Identify the various blood spatter pattern
1
3
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Describe the methods used in tidentification and individualisation of blo
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Blood
Fresh
Old & dried
Obvious
Obvious?
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Whose blood is it?
Show up invisible stainsIs it blood?1
3
Is it human blood?
Can we use blood spatterpatterns to reconstruct events?
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2
Blood
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Blood Composition
Fresh frblood p
Fluid portion of blood
55% by weight
Transport system
8% of body weight
Blood plasma
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Blood Composition Left to right: erytthrombocyte, le
Blood cells
Oxygen transport
Red blood cells / erythroc
8% of body weight
Blood plasma
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Blood Composition Left to right: erytthrombocyte, le
White blood cells / leukoc
Immune response
Blood cells Red blood cells / erythroc
8% of body weight
Blood plasma
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Blood Composition Left to right: erytthrombocyte, le
Clotting response
Platelets / thrombocytes
White blood cells / leukoc
Blood cells Red blood cells / erythroc
8% of body weight
Blood plasma
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Erythrocytes
7.8 microns in diameter
No nucleus
Biconcave
No DNA Red bloo
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Erythrocytes
Principle function
4 oxygen moleculeson each protein
Oxygen transport
Red bloo
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Antigens
Proteins on surface of red blood cells
Over 100 rare antigens
30 commonly occurring antigens
Responsible for blood typing
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Blood transfusion
Must be given blood of the right type
Early days Some people fine aftera blood transfusion
Some people fell ill or dieafter a blood transfusion
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Karl Landsteiner
Karl Land
Developed the A-B-Oblood typing system
Won the 1930 NobelPrize in Medicine
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A-B-O Blood Types
Occurrence of blood types vary
Blood Type Percentage (%)
O 40
A 25
B 30
AB 5
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Blood Types & Personality
No
Is your blood typethe key to true love?
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Blood Types & Personality
“I am type B and
have the tendency
to be simplistic and
straightforward at
times.” - Ryu Matsumoto
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Antibodies
20% of bloodplasma volume
Immunoglobins
Produced as part ofimmune response
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Antibodies
Antigen binding sites
Bind to “alien” objects
Extremely specific
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Serum Antibodies
Antibodies corresponding to surface antige
Anti-A antibodies
Anti-B antibodies
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Blood typing system
Many different antigens
A-B-O system based on A and B antige
Less common antigens
D antigen / rhesus antigens
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Rhesus antigens
Rhesuspositive
With D antigen Without D antig
Rhesusnegative
85% of population 15% of populat
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Blood Type Distribution in Singapore
Blood Type Percentage (%)
O+ 34
O- 6
A+ 21
A- 4
B+ 25.5
B- 4.5
AB+ 4
AB- 1
Want to indivievidence
Blood types not individuali
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Bio-Identification
Individualisation of blood type?
More complex blood typing
Inferior to DNA fingerprinting
Blood sample Individualise it
Extensive research before 1990
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Bio-Identification
Cannot be used to prove guilt
Can be used to establish innocence
Blood type not individualised
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Bio-Identification
Crime scene Type A blood found
Established innocence
Suspect is type B blood