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chapter 3-4
| Question | Answer |
|---|---|
| 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
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