Chapter 3: The Study of Hair

Question 1

Hair is considered as what kind of two evidences?

Answer 1

• Trace Evidence
• Class Evidence

Question 2

Characteristics of Hair

Answer 2

• can be easily left behind
• secondary transfer (common w/ animal hair)
• does not easily compose
• offers clues to racial background
• chemical tests (drugs, heavy metals, nutritional deficiencies)
• DNA (if follicle is present)

Question 3

What is the function of hair?

Answer 3

• regulates body temperature
• decreases friction
• protects against sunlight
• acts as a sense organ

Question 4

Structure of Hair

Answer 4

• Hair shaft
• Sebaceous Gland
• Follicle
• Papilla

Question 5

Follicle

Answer 5

structure in the skin

Question 6

Hair Shaft

Answer 6

made of (Keratin) > a protein produced in the skin

Question 7

Papilla

Answer 7

contain the blood vessels that supply the nutrients to feed the hair & help it grow

Question 8

Sebaceous Gland

Answer 8

secretes oil & helps to keep the hair conditioned

Question 9

Keratin

Answer 9

made up of amino acids in a spiral shape

Question 10

Hair Shaft

Answer 10

• Cuticles
• Cortex
• Medulla
• Pigment granules made of melanin

Question 11

3 Layers of the Hair Shaft

Answer 11

1. Cuticle
2. Cortex
3. Medulla

Question 12

Cuticle

Answer 12

• the transparent outer layer of the hair shaft
• made up of scales that overlap each other and protect the inner layers of the hair
• human hair has a cuticle scales that are flattened & narrow which are called imbricated (animal hair is diff.)

Question 13

Cortex

Answer 13

• the largest part of the hair shaft
• part of the hair that contains the pigment or melanin that gives the hair its color
• amount of pigment varies from person to person

Question 14

Medulla

Answer 14

• center of the hair
• can be hollow or filled w/ cells
• 5 diff. medulla patterns

Question 15

Medulla Patterns

Answer 15

1. Continuous
2. Interrupted (Intermittent)
3. Fragmented or Segmented
4. Solid
5. None

Question 16

Continuous

Answer 16

one unbroken line of color

Question 17

Interrupted (Intermittent)

Answer 17

pigmented line broken at regular intervals

Question 18

Fragmented or Segmented

Answer 18

pigmented line unevenly spaced

Question 19

None

Answer 19

no separate pigmentation in the medulla

Question 20

How can hair vary?

Answer 20

• Shape
• Length
• Diameter
• Texture
• Color

Question 21

Head Hair

Answer 21

circular or elliptical cross section

Question 22

Eyebrows & Eyelashes

Answer 22

circular w/ tapered ends

Question 23

Beard Hair

Answer 23

thick & triangular/coarse/double medulla
- underarm
- body hair

Question 24

What happens w/ treated hair?

Answer 24

• bleaching hair removes pigment & gives hair a yellow color (hair is brittle/disturbs the scales on cuticle)
• changes the color of the hair shaft
• cuticle & cortex take on the color of the dye

Question 25

Racial Differences

Answer 25

- beard racial categorization can be made by identifying certain characteristics of hair - characteristics may not be applicable to all individuals in these groups - individual hair cannot be assigned to any of these groups

Question 26

Animal Hair

Answer 26

- pigment is denser toward the medulla - bonded color patterns - medulla: thicker

Question 27

Human Hair

Answer 27

- pigment is denser toward the cuticle - no bonded color patterns - usually one color

Question 28

Medulla Index

Answer 28

- diameter of medulla/diameter of the entire hair - index < .5 human hair

Question 29

How are hair samples collected during an investigation?

Answer 29

- plucked - shaving - scrapping - placing tape over the surface so that hair sticks to it - vacuum large surfaces

Question 30

Life Cycle of Hair

Answer 30

- Anagen - Catagen - Telogen

Question 31

Anagen

Answer 31

- lasts 1,000 days - 80-90% of human hair is in this stage - active growth

Question 32

Catagen

Answer 32

- 2% - hair grows & changes/turns grey

Question 33

Telogen

Answer 33

- 10-18% - hair follicle is dormant. hair is easily lost

Question 34

How do you analyze a hair sample?

Answer 34

1. Macroscopically 2. Microscopically 3. Fluorescence Microscope

Question 35

Macroscopically

Answer 35

hair length, color & curliness (naked eye)

Question 36

Microscopically

Answer 36

pattern of the medulla, pigment of the cortex & types of scales on the cuticles

Question 37

Fluorescence Microscope

Answer 37

can detect dyes & hair treatments

Question 38

Neuron Activation Analysis

Answer 38

- used to identify 14 different elements in a 2cm long strand of hair - high energy neutrons bombard the hair - Cu, Au, Mn, Na, Ag, Sb, Ar, Br - Probably of 2 ppl having the same concentration of 9 diff. elements is 1 in a million

Question 39

Why is hair follicle important?

Answer 39

- blood & tissue attached to the follicle can be analyzed - DNA analysis

Question 40

Another name for a hair follicle is the....

Answer 40

called follicular tag

Question 41

The hair shaft is considered what kind of evidence?

Answer 41

Class evidence

Question 42

How can you test for substances in the hair shaft?

Answer 42

- hair grows out of the skin & the chemicals that the skin absorbs can become Incorporated in the hair - chemicals, toxins and drugs and be detected