trace evidence (hair and fibers) Flashcards
what can one hair determine? (7)
•if source is a human or an animal
•race (sometimes)
•location from where the hair came from
•whether the hair was forcibly removed
•chemical treatments?
•if drugs have been ingested
•environmental exposure
what is the hair shaft composed of?
cuticle (outer layer)
cortext (inner layer)
medulla (very inside layer)
what is the cuticle?
the outside covering made of overlapping scales
what is the cortex?
the inner layer made of keratin and imbedded with pigment that gives the hair its shape
what is the medulla?
the inside layer running down the center of the cortex
what are the three basic scale patterns?
coronal, spinous, imbricate
what are the two major cortex characteristics?
melanin
cuticle fusi
what is melanin?
pigment granules that give hair its color
what is the cuticle fusi?
air spaces that are usually found near the root
what are the five medulla patterns?
intermitted or interrupted (• • •)
fragmented (••• ••• •••)
continous (•••••••••)
stacked
absent
how to find to medullary index?
diameter of medulla divided by diameter of the hair
medullary index for humans is generally less than … and for animals its usually greater than …
⅓
½
what are the three different hair shapes and what texture do they give the hair?
round- straight
oval- curly
crescent moon- kinky
what is anagen hair?
hair that is actively growing (lasting up to five years)
what is catagen hair?
hair that is not growing (a resting phase)
what is telogen hair?
hair that is dying and ready to fall out
the root contains … DNA and the hair shaft contains … DNA
nuclear
mitochondria
what are some example of synthetic fibers? (7)
•rayon
•nylon
•acetate
•acrylic
•spandex
•polyester
•dacron
what are some examples of natural fibers? (6)
•silk
•cotton
•wool
•mohair
•cashmere
•linen
what is yarn?
a continous strand of fibers or filaments, either twisted or not
what is a warp?
lengthwise yarn
what is a warp?
lengthwise yarn
what is a weft?
crosswise yarn
what is a blend?
a fabric made up of two or more
what are the three weave patterns?
plain (checker board)
satin (stair steps)
twill (picnic basket weave)
