Identification of Body fluids Flashcards
Plasma
Fluid portion of blood that contains the cellular components
Serum
Liquid portion of blood that does not clott
Erythrocytes (RBC)
Red Blood Cells, carry stuff
Leukocytes (WBC)
White Blood Cells, defend against foreign substances
Platelets
Important components in clotting
Exsanguination
Bleeding to death
Hard, smooth surfaces (Glass, smooth tile)
Surfaces that create little spatter
Rough surfaces (wood, concrete)
Surfaces that create lots of spatter
Narrow end of a blood stain
Indicates direction of travel
Area of Convergence
2D area in which blood stain originated, found by using strings to the long axis of blood stains
Area of Orgin
3D area in which blood stains originated, found by examining the angle of impact and using strings going in the direction of travel at the correct angle.
Round stains
Stains that have 90 degree angle of impact
0.5 w/l
Elliptical stain with 30 degree angle of impact
Width/Length
Ratio for discovering angle of impact
Gunshot wounds
Indicated by back and possibly front spatter and fine misting. Misting is typical of gunshots and not seen in too many other instances
Stabbing/Beating wounds
Larger spatter aroun 1-3 mm, varies depending on weapon
Castoff stains
Blood is thrown from a weapon used in a beating. These stains are typically linear and large
Splashed/ Projected Blood
Large central area with peripheral spatters. Spattering blood tends to leave narrow projections
Expirated Blood
Mist/spatter of blood due to coughing or vomiting. May contain mucous, be slightly dilute and contain air bubble. Air bubbles are a decent indication of expirated blood.
Arterial Blood
May take on many types due to the severity of the injury. ( gushing, spurting, or spraying)
Transfer Blood
Wet blood contacts an object and leaves a pattern. Requires testing to indicate the patter is correct
Red, Reddish brown, black
Color changes of blood as it ages
3-15 minutes
Blood begins to clot in
Void
Area with no blood on it while surrounded by blood. Indicates that an object has been moved
Passive Blood Stains
Caused by transfer of blood from an area, flow patters, and saturation stains
Active Blood Stains
Caused by impact, arterial spurts, expirated and castoff stains
ABO
Classification of blood types based on the reactions of antibodies and antigens
Serology
The laboratory study of body fluids using specific antigen and serum antibody reactions
Agglutination
Process of red blood cells clumping together in response to an antibody
Precipitin Test
Test that distinguishes between human and animal blood
Benzidine test
A regent once widely used as a presumptive test for blood. Involved using ethanol/acetic acid solutions which turned blue when the reagent and blood were added.
Hemastix test
Commercial test strip that can be used as a presumptive test for blood. Designed to detect blood in urine but works well in forensic settings
Phenolphthalein Test
A presumptive test for blood that turns pink when blood is added to the reagent.
Luminol/Flourescein tests
Presumptive blood test based on chemical reactions that cause light to be emitted from the blood stain
Crystal tests
A type of presumptive test in which a positive result is the formation of a solid crystalline substance
Seminal Acid Phosphate
Enzyme found in abundance in seminal fluid. Commonly tests for when testing for semen.
Alpha-amylase
Enzyme found in saliva that is the basis for presumptive tests for that fluid. (Starch-iodide tests are common)
Periodic acid-Schiff reagent
Presumptive test for the presence of vaginal material, glycogenated cells are stained bright magenta.
Azostix
Test used forensically to detect urine. Commercially used to detect blood in urine. (Urine tests are inaccurate and not common in forensic science)
Cyanide
A black colored stomach mucosa is associated with…
Barr bodies (condensed 2nd X chromosome)
Sex can be determined by examining hair for what?
Lightening
Branching tree on the front of the chest is usually caused by
Liver
Which organ is least likely to be injured by a blast wave?
