Forensics: Unit 4. 5 million hairs on your body!!! Blondes have about 120,000 on their head ...
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Transcript of Forensics: Unit 4. 5 million hairs on your body!!! Blondes have about 120,000 on their head ...
![Page 1: Forensics: Unit 4. 5 million hairs on your body!!! Blondes have about 120,000 on their head Brunettes have about 100,000 Red heads have about.](https://reader034.fdocuments.in/reader034/viewer/2022051417/5697bfd71a28abf838cae4ee/html5/thumbnails/1.jpg)
Hair Analysis
Forensics: Unit 4
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5 million hairs on your body!!! Blondes have about 120,000 on their head Brunettes have about 100,000 Red heads have about 80,000 Lose 100 hairs a day from your scalp
Hair Morphology
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Hair is made of complex cross-linked protein
polymers… primarily keratin. Grows from underneath the skin… attached to
blood supply. 3-5 year lifespan. Grows 1cm/month.
Hair Morphology
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What’s inside???
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Cuticle
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Cortex
• The Cortex holds the pigments of the hair as well as tiny air pockets within the hair, called cortical fusi.
• Four color pigments found in human hair: red, yellow, brown, and black.
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Not found in all hairs. Can be continuous or interrupted. Never more
than 1/3 space of hair in a human. More commonly found in people w/ Asian or
Native American decent.
Medula
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The tip naturally rounds over a 3 week period.
Hair Tip
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Looks differ ripped out versus falling out
Hair Root
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Hair in cross-section
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Round hair has no twisting and is typically
very straight. Found in people of Asian and Native American
descent
Round Hair
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Oval hair can show some twisting or
undulation, which creates a wavy appearance. Typically found in Caucasians, Mexicans, and
Middle Eastern people.
Oval Hair
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Hair that is crescent shaped and/or almost
flat. This hair typically twists on itself or has large
amounts of undulation. Typically found in people
of African descent.
Crescent Hair
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Often triangular in cross-section.
Beards sometimes feel “sharp” for this reason.
Facial and Body Hair
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Stage 1: Anagen Phase
Last 3-5 years… hair has a defined root, connected to blood supply, and grows out of the skin.
Stage 2: Catagen Phase Intermediate phase… hair stops growing. Lasts 3-6
weeks
Stage 3: Telogen Phase Last 3-5 months of a hair. Loses connection to blood
supply and follicle slowly pushes it out.
Stages of Hair Growth
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Stages Hair Growth
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Human hair ranges from 25-125 micrometers
in diameter. Thicker hair grows slower than fine hair, but
falls out less easily.
Hair Thickness
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Hair quality can be affected by dryness, lack
of conditioner, bleaches, straighteners, overuse of blow dryer (too hot), etc.
Lack of care