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Forensics Science > Chapter 3: The Study of Hair > Flashcards

Chapter 3: The Study of Hair Flashcards

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Biology 101 flashcards
1
Q

Hair is considered as what kind of two evidences?

A
  • Trace Evidence
  • Class Evidence
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2
Q

Characteristics of Hair

A
  • 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)
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3
Q

What is the function of hair?

A
  • regulates body temperature
  • decreases friction
  • protects against sunlight
  • acts as a sense organ
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4
Q

Structure of Hair

A
  • Hair shaft
  • Sebaceous Gland
  • Follicle
  • Papilla
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5
Q

Follicle

A

structure in the skin

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6
Q

Hair Shaft

A

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

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7
Q

Papilla

A

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

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8
Q

Sebaceous Gland

A

secretes oil & helps to keep the hair conditioned

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9
Q

Keratin

A

made up of amino acids in a spiral shape

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10
Q

Hair Shaft

A
  • Cuticles
  • Cortex
  • Medulla
  • Pigment granules made of melanin
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11
Q

3 Layers of the Hair Shaft

A
  1. Cuticle
  2. Cortex
  3. Medulla
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12
Q

Cuticle

A
  • 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.)
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13
Q

Cortex

A
  • 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
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14
Q

Medulla

A
  • center of the hair
  • can be hollow or filled w/ cells
  • 5 diff. medulla patterns
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15
Q

Medulla Patterns

A
  1. Continuous
  2. Interrupted (Intermittent)
  3. Fragmented or Segmented
  4. Solid
  5. None
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16
Q

Continuous

A

one unbroken line of color

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17
Q

Interrupted (Intermittent)

A

pigmented line broken at regular intervals

18
Q

Fragmented or Segmented

A

pigmented line unevenly spaced

19
Q

None

A

no separate pigmentation in the medulla

20
Q

How can hair vary?

A
  • Shape
  • Length
  • Diameter
  • Texture
  • Color
21
Q

Head Hair

A

circular or elliptical cross section

22
Q

Eyebrows & Eyelashes

A

circular w/ tapered ends

23
Q

Beard Hair

A

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

24
Q

What happens w/ treated hair?

A
  • 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
25
Q

Racial Differences

A
  • 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
26
Q

Animal Hair

A
  • pigment is denser toward the medulla
  • bonded color patterns
  • medulla: thicker
27
Q

Human Hair

A
  • pigment is denser toward the cuticle
  • no bonded color patterns
  • usually one color
28
Q

Medulla Index

A
  • diameter of medulla/diameter of the entire hair
  • index < .5 human hair
29
Q

How are hair samples collected during an investigation?

A
  • plucked
  • shaving
  • scrapping
  • placing tape over the surface so that hair sticks to it
  • vacuum large surfaces
30
Q

Life Cycle of Hair

A
  • Anagen
  • Catagen
  • Telogen
31
Q

Anagen

A
  • lasts 1,000 days
  • 80-90% of human hair is in this stage
  • active growth
32
Q

Catagen

A
  • 2%
  • hair grows & changes/turns grey
33
Q

Telogen

A
  • 10-18%
  • hair follicle is dormant. hair is easily lost
34
Q

How do you analyze a hair sample?

A
  1. Macroscopically
  2. Microscopically
  3. Fluorescence Microscope
35
Q

Macroscopically

A

hair length, color & curliness (naked eye)

36
Q

Microscopically

A

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

37
Q

Fluorescence Microscope

A

can detect dyes & hair treatments

38
Q

Neuron Activation Analysis

A
  • 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
39
Q

Why is hair follicle important?

A
  • blood & tissue attached to the follicle can be analyzed
  • DNA analysis
40
Q

Another name for a hair follicle is the….

A

called follicular tag

41
Q

The hair shaft is considered what kind of evidence?

A

Class evidence

42
Q

How can you test for substances in the hair shaft?

A
  • 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

Forensics Science (7 decks)

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