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chapter 3-4

What is keratin a protein in keeping hair strong and flexible
what is the rate of human hair growth 1.3 cm per month
Describe the 3 stages of hair growth in detail Anagen Phase- active growth phase; Catogenic Phase- hair grows and transitions; Telogenic Phase- resting phase and hairs are lost in this phase
Distinguish between European, Asian, and African hair European- generally straight or wavy, pigment distributed small; Asian- straight, pigment densely distributed; African- kinky, curly, or coiled, pigment densely distributed
What are the three parts of the shaft of the hair cuticle, cortex, medulla
How do the scales on the cuticle normally point they overlap each other
How do the scales on the cuticle point when drugs have been ingested from proximal to distal end
Name and describe the three types of scale patterns Coronal- often resemble a stack of paper cups; Spinous- triangular in shape and protrude from the shaft; Imbricate- flattened and narrowed
What is the medullary index the fraction of the hair shaft's diameter that the medulla occupies
What is the effect of bleaching on the hair Removes pigment granules and gives hair a yellowish color, makes hair brittle and disturbs scales on cuticle
What is the importance of the root in forensics it has DNA on it
5 types of medullas Continuous- one unbroken line; Interrupted- pigment broken at regular intervals; Fragmented- pigment line unevenly spread; Solid- fills whole area; Absent- no separate pigmentation
Why do CSI's need 25-50 hairs to be considered adequate to represent the range pf hair characteristics of that individual
What can be determined from hair If the source is human or animal, race, whether the hair was forcibly removed, if the hair has been treated with chemicals
How does human hair differ from animal hair pattern of pigmentation, meduallary index, cuticle type
What is the importance of fibers in criminal cases it can link a crime and a suspect
How can fibers be identified microscope, burn test
Distinguish between natural and synthetic fibers natural- come from animals, plants, and minerals that are mined from the ground synthetic- fake fibers or regenerated fibers and polymers.. ex polyester, nylon, acrylic
Three types of natural fibers plant-cotton; animal- hair, fur, webbing-ex- fur, silk, wool
Why should care be taken when collecting hairs and fibers because you don't want to lose valuable evidence
Name 5 characteristics of fibers that can be identified using a microscope type of fiber, color of fiber, where it was found , what type of crime was committed, time between crime and discovery of fiber.
Created by: hwheel