Body Fluids Flashcards
Name the 6 principal body fluid stains.
Blood Saliva Semen Urine Faeces Vomitus
Violent crime stains
Blood=clothing, weapon/individual
Saliva=clothing
Volume crime stains
Blood=broken glass
Saliva=cigarette butt
Faeces
Sexual assault stains
Semen=clothing, bedding, a swab of vagina, anus
Saliva= clothing, skin
Vaginal= digital or penile swap
Faeces= digital or penile swap
Stain colour
Saliva=off white Semen= off white Blood= red/brown Urine=yellowish Faeces=brownish
Alternative light sources
Most organic materials fluoresce under certain wavelengths
Blue/green useful
Rapid and inexpensive
unlikely to cause damage to DNA (except UV)
Body fluid testing protocol
- where+what?=presumptive
- human?=confirmatory
- whose?=HID testing
Kastle Meyer evidential value and cost
cheap
simple
rapid(2mins)
limited evidential value
RSID evidential value and cost
variable price
complex
rapidity variable
greated evidential value
HID evidential value and cost
expense variable (DB=£35, volume crime=£250, FISH/LMD= £10,000) rapidity variable (min 8 hours, 3-5 days standard) extremely strong evidential value)
What does blood transport?
What other roles does blood have?
O2
nutrients
waste
osmolarity
temperature regulation
immunity/injury functions
What is the scientific name for red blood cells?
erythrocytes
What percentage of blood volume are RBC’s?
48%
Do RBC’s have DNA?
no
What do RBC’s consist of?
membrane, haemoglobin (iron-containing metalloprotein, 4 subunits), cytoplasm
What is the scientific name for White blood cells?
Leucocytes
What percentage of blood volume are WBC’s?
1%
What is the role of WBC’s?
protect the body from infection
What is the structure of WBC’s?
nucleated
Name 4 subtypes of white blood cells?
macrophages, lymphocytes(B+T), neutrophil, eosinophil
What is the scientific name for platelets?
Thrombocytes
What are platelets?
blood clotting, non-nucleated, cell fragments formed in bone marrow, injury allows platelets to become activates, change of shape, causes clumping
Name 4 blood presumptive tests?
Kastle Meyer
Leucomalachite green
luminol/blue star (at scenes)
tetramethylbenzidine (hemastix)
What is the equation which shows peroxidase activity?
2H2O2—>2H20+02
Kastle Meyer
pink
1) ethanol = increases sensitivity
2) Kastle Meyer
3) hydrogen peroxide
Leucomalachite green
blue/green
1) leucomalachite green
2) hydrogen peroxide
Hemastix
green/blue/black 1 part testing kit containing: -tetramethylbenzidine -disopropylbenzene dihydroperoxide originally designed for detection of blood in urine
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
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
What are 5 false positives of blood?
horseradish potato red onion tomato bleach
What percentage of saliva is water?
99% water
What is the pH range of saliva?
6.8-7