How can we help?

You can also find more resources in our Help Center.

20 terms

Chapter 5

Hair
STUDY
PLAY
Locard Exchange Principle
Whenever two objects come into contact with one another, there is exchange of materials between them.
Morphology
form and structure
Polymer
A molecule consisting of many identical repeating unit; polymers can be naturally occurring or synthetic
Cuticle
Tough, clear outside covering of the hair shaft
Cortex
Middle layer of the hair shaft that provides strength; comprises most of the hair mass
Medulla
The spongy interior core of hair that gives it flexibility; appears as a canal in the middle of the shaft.
Keratin
A tough protein polymer made up of about 20 different amino acids. The principal one is cystine, which allows strong disulfate bonds to form between protein chains. This cross-linking makes hair so resistant to chemical and biological degradation. All that sulfur in Keratin also accounts for the distinctive smell of burning hair.
Cortical Fusi
Irregularly shaped air spaces in the cortex
Undulation
In hair morphology, slight waviness
Micrometer
One millionth of a meter or one thousandth of a millimeter
Anagen Phase
Period of growth in the hair cycle, averaging 3 to 5 years
Catagen Phase
Intermediate period of hair growth, lasting about 3 weeks.
Telogen Phase
Final phase in hair growth, resulting in the loss of hair over about 3 months
Interference Patterns
Patterns that demonstrate the wave nature of light, resulting from constructive(additive) and destructive combinations of light waves. This happens when a small object deflects coherent light so the wave fronts travel different directions. This phenomenon is called diffraction.
Melanin
A natural pigment found in the skin. Ultraviolet rays in sunlight make it more concentrated, causing tanning
Association
A link between an unknown sample and known evidence.
Questioned
Term used in forensics to describe a sample of unknown origin; for example, a hair was found on a jacket, but we do not know whose head it came from.
Exemplar
Term used in forensics to describe a sample of known origin; for example, a hair was found on a jacket, but we do not know whose head it came from.
Metabolite
A specific product of a substance, formed by chemical processes in the body
False Positive
A test result that comes out positive when it should not; often caused by contamination or lack of a running control.