1. Forensics: Unit 4

2.   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

3.   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

4.  What’s inside???

5.  Cuticle

6.  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.

7.   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

8.   The tip naturally rounds over a 3 week period. Hair Tip

9.   Looks differ ripped out versus falling out Hair Root

10.  Hair in cross-section

11.   Round hair has no twisting and is typically very straight.  Found in people of Asian and Native American descent Round Hair

12.   Oval hair can show some twisting or undulation, which creates a wavy appearance.  Typically found in Caucasians, Mexicans, and Middle Eastern people. Oval Hair

13.   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

14.   Often triangular in cross-section.  Beards sometimes feel “sharp” for this reason. Facial and Body Hair

15.   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

16.  Stages Hair Growth

17.   Human hair ranges from 25-125 micrometers in diameter.  Thicker hair grows slower than fine hair, but falls out less easily. Hair Thickness

18.   Hair quality can be affected by dryness, lack of conditioner, bleaches, straighteners, overuse of blow dryer (too hot), etc. Lack of care