Chapter 5 Hair Test Review
1.
List the three basic scale patterns for hair.
coronal, spinous, imbricate
2.
List the five types of medulla patterns.
Interrupted (intermittent), fragmented,
continuous, stacked, absent
3.
What can microscopic examination of hair
determine? If it is human or animal hair, racial origin (sometimes),
location on the source’s body, whether the hair has been chemically
treated, whether the hair has been forcibly removed, what color it is,
what shape it is, what medulla type, medulla index, scale type, etc.
4.
How can human hair be distinguished from animal hair? Human
medullas have an index of < 1/3 while animal medullas have an index of
> ½. Also, humans only have imbricate scales and can only have
fragmented, continuous or absent medullas.
5. List and explain the three parts of the hair shaft. Cuticle—outside
covering, made of overlapping scales. Cortex—inner layer made of
keratin and embedded with pigment; also contains air sacs called
cortical fusi. Medulla—inside layer running down the center of the
cortex.
6. How can you tell if the hair is dyed? Dyed hair has color in
cuticle and cortex; Bleaching removes pigment and gives a yellow tint
7. List the three growth phases of the hair and what each represents.
Anagen—hair is actively growing; lasts up to 5 years; Catagen—hair is
8.
not growing; a resting phase; Telogen—follicle is getting ready to push
the hair out; lasts two to six months
Where can nuclear DNA be found in the hair? In the root of the hair
follicle
9.
Define the following terms:
Cuticle: tough, clear outside covering of the hair shaft
Dermis: layer of skin from which the hair grows
Melanin: natural pigment found in the skin
Sebaceous: oil glands
Follicle: structure from which the hair grows
Viscosity: resistance to flow
Density: measurement of mass per unit of volume
10.
How can the race be determined by hair structure? Can be
straight, curly, or kinky, depending on the cross-section, which may be
round, oval, or crescent-shaped.
11. How much does the average hair grow in a month? 1 cm per month;
approximately one-half inch per month