Body Fluids Flashcards
1
Q
Name the 6 principal body fluid stains.
A
Blood Saliva Semen Urine Faeces Vomitus
2
Q
Violent crime stains
A
Blood=clothing, weapon/individual
Saliva=clothing
3
Q
Volume crime stains
A
Blood=broken glass
Saliva=cigarette butt
Faeces
4
Q
Sexual assault stains
A
Semen=clothing, bedding, a swab of vagina, anus
Saliva= clothing, skin
Vaginal= digital or penile swap
Faeces= digital or penile swap
5
Q
Stain colour
A
Saliva=off white Semen= off white Blood= red/brown Urine=yellowish Faeces=brownish
6
Q
Alternative light sources
A
Most organic materials fluoresce under certain wavelengths
Blue/green useful
Rapid and inexpensive
unlikely to cause damage to DNA (except UV)
7
Q
Body fluid testing protocol
A
- where+what?=presumptive
- human?=confirmatory
- whose?=HID testing
8
Q
Kastle Meyer evidential value and cost
A
cheap
simple
rapid(2mins)
limited evidential value
9
Q
RSID evidential value and cost
A
variable price
complex
rapidity variable
greated evidential value
10
Q
HID evidential value and cost
A
expense variable (DB=£35, volume crime=£250, FISH/LMD= £10,000) rapidity variable (min 8 hours, 3-5 days standard) extremely strong evidential value)
11
Q
What does blood transport?
What other roles does blood have?
A
O2
nutrients
waste
osmolarity
temperature regulation
immunity/injury functions
12
Q
What is the scientific name for red blood cells?
A
erythrocytes
13
Q
What percentage of blood volume are RBC’s?
A
48%
14
Q
Do RBC’s have DNA?
A
no
15
Q
What do RBC’s consist of?
A
membrane, haemoglobin (iron-containing metalloprotein, 4 subunits), cytoplasm
16
Q
What is the scientific name for White blood cells?
A
Leucocytes
17
Q
What percentage of blood volume are WBC’s?
A
1%
18
Q
What is the role of WBC’s?
A
protect the body from infection
19
Q
What is the structure of WBC’s?
A
nucleated
20
Q
Name 4 subtypes of white blood cells?
A
macrophages, lymphocytes(B+T), neutrophil, eosinophil
21
Q
What is the scientific name for platelets?
A
Thrombocytes
22
Q
What are platelets?
A
blood clotting, non-nucleated, cell fragments formed in bone marrow, injury allows platelets to become activates, change of shape, causes clumping
23
Q
Name 4 blood presumptive tests?
A
Kastle Meyer
Leucomalachite green
luminol/blue star (at scenes)
tetramethylbenzidine (hemastix)
24
Q
What is the equation which shows peroxidase activity?
A
2H2O2—>2H20+02
25
Kastle Meyer
pink
1) ethanol = increases sensitivity
2) Kastle Meyer
3) hydrogen peroxide
26
Leucomalachite green
blue/green
1) leucomalachite green
2) hydrogen peroxide
27
Hemastix
```
green/blue/black
1 part testing kit containing:
-tetramethylbenzidine
-disopropylbenzene dihydroperoxide
originally designed for detection of blood in urine
```
28
Luminol
```
fluorescent reaction
single spray containing:
-luminol
-sodium perborate
-water+sodium carbonate
sprayed directly
may dilute stain
luminol oxidised to 3-aminophthalate
gives fluorescence in 30secs
used when staining is not visible
```
29
What are 5 drawbacks of presumptive tests?
```
only indicators
lack sensitivity
too sensitive in some cases
non-human specific
false positives and false negative reactions
```
30
What are 5 false positives of blood?
```
horseradish
potato
red onion
tomato
bleach
```
31
What percentage of saliva is water?
99% water
32
What is the pH range of saliva?
6.8-7
33
What enzyme is in salvia that helps break down food?
alpha-amylase
34
What are the functions of saliva?
allows bows formation
aids passage of food and begins digestion of starches
bioindicator
-alpha-amylase
-found in saliva+pancreas
-beta amylase present in some microorganisms
35
What is the test for starch in saliva?
Starch-iodine test
36
What colour indicates a positive result in the starch-iodine test?
blue/purple then yellow/brown when starch has been digested by amylase present
37
How do you locate and test if saliva is present?
phadebas amylase tests, phadebas paper, amylopectin coupled to blue dye immobilised onto paper, when placed on sample + incubated, saliva will cause the dye to separate from paper, producing blue spot.
38
What are the 3 fluids present in semen?
seminal fluid (60-70%)
fluid from prostate (25-30%)
speratazoa (2-5%)
39
What is it called when a male produces very few sperm?
Oligospermia
40
What is it called when a male produces no sperm?
Azoospermia
41
Semen
contains cellular, organic and inorganic constituents
high level of certain enzymes
fluoresces under UV light
direct observation under the microscope
42
What is the presumptive test for semen?
Acid phosphatase test
43
What are the two solutions added in the acid phosphatase test?
Sodium a-napthyl acid phosphatase
| o-dianisdine
44
What are the results/colours you can receive in the acid phosphatase test?
```
Positive = purple (10-15 secs)
Negative = no colour change
Inconclusive = slow development of colour
```
45
What is the confirmatory test for semen?
semen microscopy
46
Characteristics of human sperm
length = 50-70 microns
head = pear shaped
4-5um long, 2-3um wide
47
What are the two most common stains for semen microscopy?
```
H&E - Hematoxylin/Eosin
-stains sperm blue/purple
Christmas tree stain
-dyes heads red
-dyes tails green
```
48
What is the presumptive test for faeces?
responds to Edelman's test for Urobilinogen
causes fluorescent reaction
can normally tell by colour, texture, smell
49
What is the presumptive test for urine?
test for pepsin
50
Is urine acidic or alkaline?
acidic
51
Is urine likely or unlikely to produce a DNA profile?
unlikely
52
What are the two substances that urine mostly consists of?
water and salts
53
Test for urine?
reacts with DMAC to form purple colour
| creatine (pritric acid forms red colouration)
54
What are the strengths of presumptive tests?
speed
cost
location
simple
55
What are the weaknesses of presumptive tests?
non-specific
false positives and negatives
weak evidential value
can dilute stain
56
What is serology?
confirmatory method specific to blood products
- blood grouping
- ABO testing
- rhesus testing
57
Name a disease that can affect the immune system.
AIDS
| Guillain-Barre syndrome
58
Is immunity innate or acquired?
both, some immunity is innate and some are acquired.
born with immunity to certain pathogens
learns pathogenic materials
59
What are antibodies?
immunoglobulins
| complex proteins that bind to specific foreign molecules
60
What are 5 variants of immunoglobins?
```
IgA = mucus, prevents pathogens into body openings
IgD = antigen receptor on B cells
IgE = allergy response, binds to allergens + triggers release of histamine
IgG = immunity against invading pathogens, this type is passed to foetus across the placenta.
IgM = present on B cells, used before IgG levels are sufficient to respond
```
61
What is an antigen?
antibody generating molecule
protein/polysaccharide molecule
present on cell membranes of invading organisms
62
Antibody-antigen behaviour
bind to specific antigens
inactivates antigen
forms insoluble clump
63
Immunochemical testing
make antibodies to specific antigen
mix with sample, sample diffuses towards antibodies
if antigen antibody match, solid formed
64
Species testing
inoculate suitable animal with human antigen + adjurant to increase response
anti-human antibodies produced
antibodies isolated, found in serum
mix antibodies with suspected human sample
if sample human-derived, reaction occurs
65
Monoclonal antibodies
```
innoculate animal with antigen
antibodies produced in spleen, removed
fuse with myleoma cells
-immortal bone cancer cells
-produces hybridoma cells
grow on culture
-harvest antibodies
-cheap and minimal animal point
```
66
What is blood grouping?
classification system based on presence or absence of antigens on blood cell membranes
- inherited
- antigens may be present on other cells
67
Name 3 systems of blood grouping.
ABO
Rhesus
Lewis
68
When and who developed the ABO system?
1900 by Landsteiner
69
Which antigen do cells have if the person is A group?
A-antigen
70
What antigen do cells have if the person is B group?
B-antigen
71
What antigen do cells have if the person is O group?
H-antigen (precursor)
72
What chromosome is the inherited trait for blood grouping carried on?
chromosome 9
73
Out of ABO, which are co-dominant, which are recessive
A and B are co-dominant, O is recessive
74
ABO testing
uses anti-serum raised against human antigens
formation of precipitate
human specific
75
What continent is blood group A common in?
European
76
What continent is blood group B common in?
Central Asia, India, Russia
77
What continent is blood group O common in?
Brazil
78
Rhesus system
1938-40
another blood antigen
85% +ve
15% -ve
79
Secretor status
80% of caucasions secrete ABO blood group antigens in body fluids
Se=dominant, secretor
se=recessive, non-secretor
80
ELISA-Enzyme -linked immuno sorbent assay (confirmatory test)
performed on a microtiter plate
plate coated with antibodies that bind to analyte
sample added , antigens bind to antibodies
second detector antibody added that binds to bound analyte (enzyme also bound)
coloured material added, positive = colour
81
Lateral flow strip tests (confirmatory test)
sample added to sample pod
capillary action causes to flow into conjugate pod
conjugate bound sample continues
melts first test line
if antigen present, binds producing coloured line.
remaining sample continues and bind to second line
82
RSID kits
```
blood, semen, saliva, urine
absorb stain on swab
extract in provided extraction buffer
mix extract aliquot with running buffer
add to RSID kit
```
