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CHY183 > Chapter 10: Hairs & Fibres > Flashcards

Chapter 10: Hairs & Fibres Flashcards

1
Q

Hair is what type of evidence?

A

Physical evidence

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2
Q

Are you able to trace human hair back to the head it was on through morphology?

A

No

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3
Q

What is another way to individual human hair?

A

Characterizing the DNA

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4
Q

Hair samples from a crime scene are accompanied by what, when being sent to the lab?

A

Standard/reference samples

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5
Q

How can hair provide a strong corroborative evidence?

A

Can place an individual at a crime scene

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6
Q

Where does hair grow from?

A

Hair is an appendage of the skin that grows out of the hair follicle

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7
Q

What are the 3 phases of hair growth?

A
  • Anagen
  • Catagen
  • Telogen
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8
Q

What are the 3 parts of the hair?

A
  • Root/bulb
  • Shaft
  • Tip
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9
Q

What are the 3 layers of the shaft?

A
  • Cuticle
  • Cortex,
  • Medulla – that is subjected to the most intense examination by the forensic scientist.
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10
Q

What is the cuticle of the hair?

A

The cuticle is the scale structure covering the exterior of the hair.

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11
Q

The scale pattern of the hair cuticle points in what direction?

A

Points towards the tip

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12
Q

How can you identify the species of hair?

A

The cuticle pattern

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13
Q

What is the cortex?

A

The cortex is the main body of the hair shaft.

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14
Q

How is the cortex important to forensics?

A

Its major forensic importance is the fact that it is embedded with the pigment granules that impart hair with colour.

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15
Q

Pigment granules are absent in what colour hair?

A

Grey hairs

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16
Q

What is the medulla?

A

The medulla is a cellular column running through the centre of the hair

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17
Q

What is the medulla index?

A

The medullary index measures the diameter of the medulla relative to the diameter of the hair shaft.

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18
Q

For human how much space does the medulla occupy?

A

For humans, the medulla generally occupies less than one-third the diameter of the shaft

19
Q

What is the follicular tag?

A

When pulled from the head, some translucent tissue surrounding the hair’s shaft near the root may be found.

20
Q

What can you use the follicular tag?

A

By using DNA analysis on the follicular tag, the hair may be individualized.

21
Q

What does the root provide?

A

Provides the tools necessary to produce hair and continue its growth.

22
Q

What is important features to identify in animal hair?

A
  • Scale structure
  • Medullary index,
  • Medullary shape
23
Q

What type of microscope is used to compare characteristics of hair?

A

The comparison microscope

24
Q

When comparing strands of human hair, the criminalist is interested in matching…

A
  • Colour
  • Length
  • Diameter
25
Q

Can the body area from which a hair originated be determined?

A

Yes. Based on the characteristics

26
Q

Can the racial origin of hair be determined?

A

Yes.

27
Q

Can the age and sex of an individual be determined from a hair sample?

A

Age cannot be determined

Sex can be if the cells are attached

28
Q

Is it possible to determine if a hair was forcibly removed from the body?

A

Yes

29
Q

At what hair growth stage is ideal for detecting DNA?

A

Anagen or early growth phase

30
Q

Where does mitochondrial DNA come from?

A

Hair shaft

31
Q

How is mitochondrial DNA transmitted?

A

From mother to child

32
Q

Forensic hair comparison involves what 2 types of hair?

A
  • Head hair
  • Pubic hair
33
Q

How many strands of hair is considered a sufficient sample?

A

25

34
Q

What are examples of natural fibres?

A
  • Wool
  • Mohair
  • Cashmere
  • Furs
  • Cotton
35
Q

What are regenerated fibers?

A

Are manufactured from natural raw materials and include rayon, acetate, and triacetate.

36
Q

What are synthetic fibers?

A
  • Are produced solely from synthetic chemicals and include nylons, polyesters, and acrylics.
  • Synthetic fibers are composed of polymers, or macromolecules, which are a large number of atoms arranged in repeating units known as monomers
37
Q

What are morphological features important in comparing fibres?

A
  • Colour
  • Diameter
  • Lengthwise striations on the surface of the fiber
  • The presence of delustering particles that reduce shine
  • The cross sectional shape of the fiber
38
Q

What is Infrared spectrophotometry?

A

Is a rapid and reliable method for identifying the generic class of fibers.

39
Q

What is a microspectrophotometer and what does it do?

A

Combines a traditional light microscope and a spectrophotometer. It allows a forensic analyst to view an object under a microscope while simultaneously obtaining its visible or infrared absorption pattern

40
Q

What is used to compare the colours of fibers through spectral patterns?

A

Microspectrophotometer

41
Q

Under a polarizing microscope what physical properties do many synthetic fibers exhibit?

A

Double refraction or birefringence

42
Q

True or false? Relevant articles of clothing (in relation to the hairs) should be packaged carefully in separate bags.

A

True

43
Q

If it is necessary to remove a fiber from an object, how is this process done properly?

A
  • the investigator must use clean forceps
  • place it in a small sheet of paper
  • fold and label the paper
  • place the paper packet inside another container.

CHY183 (17 decks)

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