chapter 3: hair analysis

cortex

middle layer that provides strength to the hair (the wood part of the pencil)

cuticle

the tough outer covering of hair that is composed of overlapping scales (yellow part of the pencil)

hair follicle

structure from which the hair grows

keratin

tough protein polymer that makes up the hair cortex

medulla

spongy interior core of the hair (graphite part of the pencil)

two parts of the hair

shaft and follicle

Three parts of hair (shaft)

cuticle, cortex, medulla

A protein that makes up majority of the cortex

keratin

sample of hair with follicle attached

example of individual evidence (contains DNA)

Hair is considered what type of evidence?

class evidence

Imbricate scales

humans

differences between human and animal hair

pattern of pigmentation, meduallary index or width, cuticle type (animals medulla is thicker)

Life cycles of hair

anagen, catagen, telogen

Anagen

The period of active hair growth

Telegen

resting phase of hair

continuous medulla

one unbroken line of color

interrupted medulla

pigmented line broken at regular intervals

fragmented medulla

pigmented line unevenly spaced

none medulla

No separate pigmentation in the medulla

Coronal scales

crown-like

Spinous scales

petal-like scales are triangular in shape and protrude from the hair shaft. They are found at the proximal region of mink hairs and on the fur hairs of seals, cats, and some other animals. They are never found in human hairs.

cat cuticle hair

dog cuticle hair

An unidentified hair is examined and found to have been dyed. The dye begins 4cms from the root. This indicates that it was dyed ___ months ago.

4

The cross section of an Africa American would appear to be ___ in shape

Crescent moon

Nuclear DNA can be identified from this part of the hair

root or follicle

A hair forcibly removed will usually have follicular tissue attached. T/F

True

The absence of ___ creates gray or white hair

melanin

Scales always point toward the ___

tip of the hair

Analytical testing methods can detect ____ use by examining the hair

drug

What does the cross section of a Native American look like?

Round in shape