Forensics Hair Test

Life cycle of hair

1. Anagen: active growth 2. Catagen: growth and changes 3. Telogen: Dormant, hairs easily lost

Six types of hair

1. Head hair 2. Eyebrow/Eyelashes 3. Beard/Mustache 4. Underarm 5. Auxiliary/Body 6. Pubic hair

The hair shaft is composed of the cuticle, cortex, and: a. medulla b. root c. crown d. granules

A. Medulla

Which of the following characteristics is found in typical Asian hair a. dark medulla b. sparsely distributed pigment granules c. flattened cross section d. hair is curly

A. dark medulla

Human hair has which type(s) of cuticle? a. imbricate b. spinous c. coronal d. pigmented

A. imbricate

Which part(s) of a hair can be analyzed for DNA? a. root b. cuticle c. medulla d. cortex

A. root

Neutron activation analysis can check hair for the presence of a. silver b. DNA c. water content d. hair dye

A. silver

Although variations can occur, which of the following best describes northern European hair? a. kinky with dense, unevenly distributed pigment b. straight with evenly distributed granules c. round cross section with a large diameter d. coarse with a thick cuticle and a continuous medulla

B. straight with evenly distributed granules

Layers of the hair shaft

Inner medulla, cortex, and outer cuticle

African hair characteristics

Kinky, curly, coiled Pigment: dense, clumped Cross-section: flattened, moderate to small diameter

Imbricate

Only in humans, flattened and narrow

Spinous

Petals

Main functions of hair

Regulates body temperature, decreases friction, protection from sunlight, and a sense organ

How can hair be collected?

Shacking, placing tape, vacuuming, plucking on surfaces

Coronal

Stack of crowns

Asian hair characteristics

Straight, continuous medulla, thick cuticle Pigment: dense distribution Cross-section: Round, large diameter, coarse shaft Color: Black

Hair follicle

The actively growing root of base of hair containing DNA and living cells

Medulla

The central core of a hair fiber

What is the cortex?

The largest part of the hair shaft that contains pigment granules (melanin)

True or False: All hairs on the head of a person are identical

False

True or False: Hair is composed of a protein called cellulose

False, Keratin

How many hair follicles do humans have when they're born?

Five million

European hair characteristics

Generally wavy/straight Pigment: small even distribution Cross-section: Oval/round Color: Blonde, red, brown, black

Length/Tip of hair types

Glass-cut Broken Cut hair Worn razor tip Scissor cut Broken hair Burned hair Razor hair

What two parts does the hair consist of?

Hair shaft, follicle

What is the cuticle scales human in human hair?

Imbricate, flattened/narrow

When was hair used as a form of class evidence?

19th century, 1934

What's a good sample size of hairs for investigation?

25-50 hairs

Comparison Microscope

A compound microscope that allows the side-by-side comparison of samples, such as hair or fibers

Neutron Activation Analysis

A method of analysis that determines composition of elements in a sample

What is the hair shaft composed of?

A protein called keratin that makes the hairs strong and flexible.

Keratin

A type of fibrous protein that makes up the majority of the cortex of a hair

Melanin Granules

Bits of pigment found in the cortex of hair

Treated hair

Bleaching: disturbs the scales on the cuticle, removes pigment

How is hair studied?

Both Microscopically and macroscopically

The period of active hair growth is called the _____ stage. a. catagen b. telogen c. anagen d. imagen

C. anagen

The cuticle scales of the hair always point towards the? a. root b. medulla c. tip of the hair d. follicle

C. tip of the hair

What can chemical tests on the hair do?

Can determine drug use/toxins, presence of heavy metals, or nutritional deficiency

What is the medulla?

Center of the hair, the medulla can be hollow, filled, continuous, doubles, absent, fragmented, pigmented, not pigmented, or segmented

Cross-section of hair

Circular, triangular, irregular, or flattened. The texture can be coarse or fine (younger)

What kind of evidence is hair when the follicle is attached?

Class evidence

Dyeing Hair

Colors the hair shaft and the cortex of the hair the same color

Which factors are used to calculate the medullary index of the hair: a. scale diameter of cuticle and the length of the hair b. width of cortex and width of medulla c. length of entire hair and the pattern of pigmentation d. width of the medulla and the width of the hair

D. width of the medulla and width of the hair

What does the hair follicle contain?

DNA

Difference in animal hairs vs. humans

Denser towards the medulla Often found in solid masses called ovoid bodies, Cuticle pattern in animals can be coronal, spinous Hair can change abruptly Medulla is much larger

What is the medullary index?

The ratio of the diameter of the medulla to the diameter of the entire hair

Cortex

The region of hair located outside of the medulla containing granules of pigment

Cuticle

The tough outer layer covering of hair composed of overlapping scales

Function of the cuticle?

Transparent outer layer of the hair shaft, made of scales that overlap to protect the inner hair layers. Scales of point to the proximal end (closest to the scalp) to the distal end (farthest from the melanin)

True or False: The cortex may contain pigment granules

True

True or False: The shaft of hair is considered class evidence in a trial

True

Which of the following is most likely a result of hair bleaching? a. increased number of disulfide bonds b. a yellowish tint to the hair c. a more triangular cross section d. thickened scales on the cuticle

b. a yellowish tint to the hair