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