Chapter 5 Hair Test Review

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Chapter 5 Hair Test Review

  1. List the three basic scale patterns for hair. 0503 copy

coronal, spinous, imbricate

  1. List the five types of medulla patterns.

Interrupted (intermittent), fragmented, continuous, stacked, absent

  1. 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.

  1. 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.

  2. 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.

  1. 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

  1. 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 not growing; a resting phase; Telogen—follicle is getting ready to push the hair out; lasts two to six months

  2. Where can nuclear DNA be found in the hair? In the root of the hair follicle

  1. 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

  1. 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.

  2. How much does the average hair grow in a month? 1 cm per month; approximately one-half inch per month

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