forensics ch 3 study guide
1) if the medullary index is .33 or less it is HUMAN hair, if it is .5 or more it is ANIMAL hair 2) For pigmentation in humans it is more dense near the cuticle, in animals pigmentation is more dense toward the medulla 3) Some animals have banded hairs and spots, humans don't
Describe 3 ways that animal hair differs from human hair
The follicle is a club shaped structure in the skin; at the end of a hair follicle is a network of blood vessels that supply nutrients to feed the hair and help it grow. The hair shaft is made up of three layers. An inner medulla, a cortex, and outer cuticle.
Describe the structure of hair
they can test it in your hair
How can police know if you have taken drugs?
imbricate cuticle
Human cuticle pattern
no medulla
No separate pigmentation in the medulla
medulla
The hair shaft is composed of the cuticle, cortex and the
False
True or False: All hairs on the head of a person are identical
False; keratin
True or False: Hair is composed of a protein called cellulose
True
True or False: the cortex may contain pigment granules
True
True or False: the shaft of the hair is considered class evidence in a trail
the regulate body temperature, decrease friction, protect against sunlight
What are the 3 functions of hair
0.44 mm
What is the rate that hair grows per day
Because hair is circumstantial evidence, it does not prove the time the person was there. The hair could have been there for weeks before the crime scene even occurred
Why does hair not necessarily prove someone guilty?
Because it can be used to identify a specific individual; hair can be used to identify a group or class with similar traits
Why is hair considered class evidence
because DNA can be found in that hair
Why is it important that police take hair from the head rather than cut it?
Because not all hairs are the same, if you take more hair you will get more accurate results
Why is it necessary to take at least 25-50 hairs for an investigation?
Straight with evenly distributed granules
although variations can occur, which of the following best describes northern european hair
imbricate
human hair has which type of cuticle
8mm/.44 = 18 days
if a womans hair measures 8mm, and dyed on august 1, how many days ago did she die?
silver
neutron activation analysis can check hair for the presence of
continuous medulla
one unbroken line of color
cuticle
outermost layer of hair
solid medulla
pigmented area filling both the medulla and the cortex
interrupted medulla
pigmented line broken at regular intervals
Fragmented medulla
pigmented line unevenly spaced
spinous cuticle
scales resemble petals as shown on the hairs of cats, seals and minks
coronal cuticle
scales that give the appearance of stacked crowns as shown on the hairs of rodents and bats
cortex
thickest layer
inner medulla, cortex, outer cuticle
what are the 3 layers of hair
this is when the hair actively grows
what is the anagen stage
this is when the hair grows and changes
what is the catagen stage
this is when the follicle becomes dormant
what is the telogen stage
beard hair
what type of hair has a double medulla
arm or leg
what type of hair is blunt
pubic
what type of hair is buckled
the width of the medulla and the width of hair (formula is Medulla legth/ hair length)
which factors are sued to calculate the medullary index of the hair?
dark medulla
which of the following characteristics is found in asian hair
yellowish tint to the hair
which of the following is most likely a result of hair bleaching
root
which parts of hair can be analyzed for DNA
tip of the hair
the cuticle scales of the hair always point toward the
anagen
the period of active hair growth is called the _______ stage
