erythrocytes
red blood cells; carry O2 throughout body, dispose CO2, contain hemoglobin
hemoglobin
allows RBC to carry O2, contain iron
leukocytes
white blood cells; immune system, defend against infection / viruses
thrombocytes
platelets; cell fragments that cluster around wounds to stop bleeding
plasma
the liquid component of blood; carries cells, hormones, nutrients, proteins, electrolytes, etc. throughout the body
presumptive test
a screening test that indicates the possible PRESENCE of a material of interest (not specific identification)
What are the presumptive tests for the presence of blood?
based on the properties of hemoglobin (iron binds to oxygen): leucocrystal violet, luminol, KASTLE-MEYER
leucocrystal violet (LCV)
a presumptive blood test that turns blood violet, used on porous surfaces (e.g. carpet blood stains)
luminol
a presumptive blood test that turns blood glowing blue, reacts with many other substances other than blood so ehhh on trustworthiness
Kastle-Meyer
the most common presumptive blood test; phenolphthalein reacts with the iron in hemoglobin
confirmatory test
a test that is SPECIFIC for the presence of a body fluid, stain, or residue of interest, and reduces or eliminates false positive results
What is the confirmatory test for blood?
relying on antigens and agglutination
What occurs when an antibody locks onto its corresponding antigens?
agglutination
antigens
structures on the surface of red blood cells
antibodies
latch onto and attack corresponding antigens, causing agglutination
Type A Blood
A antigens, B antibodies (Anti-B)
Type B
B antigens, A antibodies (Anti-A)
Type AB
BOTH A and B antigens, NO antibodies
Type O
no antigens, BOTH A and B antibodies (Anti-A and Anti-B)
What blood type is the universal receiver?
AB+ (no antibodies for A, B, or Rh or it would attack itself!)
What blood type is the universal donor?
O- (no antigens means nothing for the antibodies to latch onto)
Rhesus (Rh)
the antigen that makes a blood type positive in its presence (no Rh means a negative blood type)
Which blood type has Rh antibodies?
negative
What is transferred in blood transfusions?
blood cells (plasma with antibodies are removed, so cannot attack the receiver's blood)
blood spatter analysis
provides point of origin for blood
point of origin
location of a blood source
transfer blood spatter
when a blood source comes into contact with a surface (e.g. smears, smudges, trails)
spatter blood spatter
when a source of liquid blood travels through the air, landing on a target surface and splattering outwards
falling droplets blood spatter
droplets dropped DIRECTLY from above at a 90 degree angle (e.g. circular stains)
force and direction blood spatter
struck the surface at an angle, with an external force propelling at horizontal velocity; tail indicates direction
radial blood spatter
impact causes droplets to fly away at high speeds
height determination graph
uses standard curve to show mathematical relationship between two quantities