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Chapter 3

Forensics: The Study of Hair

QuestionAnswer
What types of evidence is hair considered to be? trace evidence and class evidence
What are the characteristics of hair? can be easily left behind, secondary transfer, does not easily decompose, offers clues to racial background, chemical tests, and DNA
What are the functions of hair? protects skin, regulates body temperature, decreases friction, and acts as a sense organ
What is Keratin? a protein produced in the skin that makes the hair strong and flexible
What does the sebaceous gland do? secretes oil and helps to keep the hair conditioned
What is the hair follicle? structure in the skin
What is does the papilla do? contains the blood vessels that supply the nutrients to feed the hair and help it grow
What is the hair shaft? it is the outer part of the hair and is made up of keratin
What are the three layers of the hair shaft? cuticle, cortex, and medulla
What is the cuticle? outside layer of the hair shaft
What is the function of the cortex and where is it located? inside; part pf the hair that gives the hair its color
What are characteristics of the medulla? runs through the center and can be hollow or filled with cells
How can hair vary? shape, length, diameter, texture, and color
Head hair circular or elliptical cross section
Eyebrows and eyelashes circular w/ tapered ends
Beard hair thick and triangular/coarse/double medulla
What happens with treated hair? bleached hair removes pigment and gives hair a yellow color, disturbs the scales on the cuticle, changes the color of the hair shaft, and the cuticle and cortex take on the color of the dye
Animal hair pigment is denser towards the medulla, banded color patterns, and a thicker medulla
Human hair pigment is denser towards the cuticle, no banded color patterns, and is usually one color
How are hair samples collected during an investigation? plucked, shave, scrapping, placing tape over the surface so that hair sticks to it, and vacuum large surfaces
Anagen lasts 1,000 days, 80-90% of human hair is in this stage, active growth
Catagen 2%, hair grows and changes/turns grey
Telogen 10-18%, hair follicle is dormant, hair is easily lost
Macroscopically viewing a hair sample hair length, color, and curliness
Microscopically viewing a hair sample pattern of the medulla, pigment of the cortex, and types of scales on the cuticle
Fluorescence microscope can detect dyes and hair treatments
Why is a hair follicle important? blood and tissue attached to the follicle can be analyzed and DNA analysis
How can you test for substances in the hair shaft? hair grows out of the skin and the chemicals that the skin absorbs can become incorporated in the hair and chemicals/toxins/drugs can be detected
Created by: margaret_05
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