Studied by 7 people
Keratin
A protein that composes hair, also found in toes and fingernails. Makes it strong and flexible
Cortex
2nd and thickest layer, also contains the most pigment. Also the most important part for determining from which person the hair came from.
Medulla
central core (may be absent)
Cuticle
Clear outer coating composed of overlapping scales
continuous medulla
one unbroken line of color
Interrupted medulla
pigmented line broken at regular intervals
fragmented medulla
pigmented line unevenly spaced
solid medulla
pigmented area filling both the medulla and the cortex
none medulla
no separate pigmentation in the medulla
Head hair
generally circular or elliptical in cross section
Eyebrows and Eyelashes
circular but often have tapered ends
Beard and mustache hair
tend to be thick and triangular
underarm hair
Can be oval or triangular
auxiliary or body hair
Can be oval or triangular
pubic hair
Can be oval or triangular
Anagen Stage
long, hair actively grows - the cells around the follicle rapidly divide and deposit materials in the hair.
Catagen stage
the hair grows and changes
Telogen stage
the follicle becomes dormant - hairs can be lost.
Imbricate
resembles a brick
coronal
shapes like a cone
spinous
looks like spines
.5 or greater
animal hair
.33 or less
person
Medullary index
medullary diameter/hair diameter
Macroscopic
investigation can indicate length, color, and curliness
Microscopic
investigation can indicate fine detail in hair structure
follicle
crucial for dna testing
Fibers
used to create a possible link between crime and suspect or to recreate a crime scene/ considered class evidence
Natural fibers
Come from plants (cotton) or animals (wool). Typically non-uniform and inconsistent in shape and structure
Manufactured fibers
Synthetics like rayon, acetate, and polyester, which are made from long chains of molecules called polymers. Typically uniform and consistent in shape and structure
Wool and Cashmere
Sheeps
Mohair
goats
Angora
rabbits
Silk
caterpillar cocoons
Plant fibers
absorb water and insoluble in water, very resistant to damage from harsh chemicals, dissolvable only by strong acids, becomes brittle over time.
Cotton
most common textile plant fiber
coir
from coconuts, is durable
Hemp, jute, and flex
from stems, grows in bundles
Manila and sisal
from leaves, deteriorates quickly
Artifical fibers
man-made fibers that originate from natural materials such as cotton or wood
Synthetic Fibers
Manufactured from chemicals, more than 50% of all fibers used in production of textile materials are synthetic or man made
Glass fiber
extremely tiny glass fibers
asbestos
group of six different materials made into fibers, fire resistant
Rayon
most common in this group imitates natural fibers, but stronger
Acetate
carpets
polyamide nylon
lightweight clothing
Polyester
polar fleece, wrinkle resistant, not easily broken down, added to natural fibers for strength
Nylon
easily broken down, similar to polyester
Acrylic
Inexpensive, balls easily, substitute for artificial wool or fur
Olefins
quick drying, resistent to wear
Chemical test
dissolves in strong acid (plant, silk, or manufactured) dissolves in strong base (wool)
Burn test
order of burning hair (animal), order of burning paper (plant), melts (manufactured)
Note
Flashcard