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 80,000 Lose 100 hairs a day from your scalp Hair Morphology
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
What’s inside???
Cuticle
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.
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
The tip naturally rounds over a 3 week period. Hair Tip
Looks differ ripped out versus falling out Hair Root
Hair in cross-section
Round hair has no twisting and is typically very straight. Found in people of Asian and Native American descent Round Hair
Oval hair can show some twisting or undulation, which creates a wavy appearance. Typically found in Caucasians, Mexicans, and Middle Eastern people. Oval Hair
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
Often triangular in cross-section. Beards sometimes feel “sharp” for this reason. Facial and Body Hair
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
Stages Hair Growth
Human hair ranges from micrometers in diameter. Thicker hair grows slower than fine hair, but falls out less easily. Hair Thickness
Hair quality can be affected by dryness, lack of conditioner, bleaches, straighteners, overuse of blow dryer (too hot), etc. Lack of care