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Chapter 3 THE STUDY OF HAIR Sept. 3, 2013

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Trichology The scientific study of the structure, function, and diseases of human hair. Very valuable in Forensic Science More resistant to decay Remains intact much longer

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Class Evidence Material that connects an individual or thing to a certain group. Cannot be used to identify a specific individual Can identify a group or class that share similar hair type. Secondary Transfer Pet hair

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Analyzing Hair Physical Characteristics: Broad racial background Chemical Characteristics: Drug use and other toxins, heavy metals, nutritional deficiencies. Follicle present, potential to recover DNA

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Individual Evidence A kind of evidence that identifies a particular person or thing DNA Fingerprint Trace Evidence: small but measureable amounts of physical or biological material found at a crime scene.

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Comparison Microscope A compound microscope that allows the side-by-side comparison of samples, such as hair or fibers Today! Neutron activation analysis and DNA fingerprinting and is considered a standard tool in trace evidence analysis.

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Function of Hair All mammals have hair. Regulate body temperature Decrease friction Protect against sunlight Sense Organ Very dense Hair=Fur

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Hair Temperature Regulation Hair and muscles work together to regulate body temp. Muscles pull hair upright, creating pockets that trap air Muscles relax and hair flattens against the body, releasing trapped air Humans are born with about 5 million hair follicles, only 2% of which are on the head. As humans age, hair density decreases

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Structure of Hair Follicle The actively growing root or base of a hair containing DNA and living cells Papilla Network of blood vessels that supply nutrients to feed the hair and help it grow. Sebaceous gland (bulb) Secretes oil to help the hair conditioned Erector muscle causes the hair to stand up

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Structure of the Hair Shaft Composed of the protein Keratin; a type of fibrous protein that makes up the majority of the cortex of a hair. Makes hair both strong and flexible Inner Medulla, Cortex, and Outer Cuticle Pencil

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Hair The Cuticle Transparent tough outer layer of the hair composed of overlapping scales. The Cortex The region of a hair located outside of the medulla containing granules of pigment (melanin) which gives the hair its color. The Medulla The center of the hair, can be hollow or filled with cells. Classify hair into 5 different groups depending on the appearance of the medulla.

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Hair Classification See Figure 3-6 on page 53 Continuous: one unbroken line of color Interrupted: Pigmented line broken at regular intervals Fragmented: Pigmented line unevenly spaced Solid : Pigmented area filling both the medulla and the cortex None: No separate pigmentation in the medulla

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Types of Hair Hair can vary in so many ways! Cross section view Textures Color Not all hairs on a persons head are exactly the same Sample of 50 from head Sample of 25 from pubic region

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Hair in Different Regions of the Body 6 Types on Human Body Head Hair Eyebrow and Eyelashes Beard and Mustache Underarm Hair Auxiliary or Body Hair Pubic Hair

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Body Hair Distinguished by their Cross-sectional Shape Head- circular or elliptical Eyebrow/eyelashes- also circular, but have tapered ends Beard- thick and triangular Body hair- oval or triangular (depending on shaved often or not) Pubic- oval or triangular

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Life Cycle of Hair 3 Stages of Development Anagen Stage : lasts approximately 1,000 days. Period of active growth when the cells around the follicle are rapidly dividing and depositing materials with in the hair. Catagen Stage : next stage as hair grows ad changes. Telogen Stage : final stage, the follicle is dormant or resting and hairs are easily lost.

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Hair Racial Differences (page 55) Animal Hair and Human Hair (page 55) Hair in an investigation Microscopy

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Substances in Hair Drug Tests Timeline 1.3 cm per month (.44 mm per day) 9 cm = approximately 7 months NAA (Neutron Activation Analysis) 14 different elements in a single 2cm long strand DNA Follicular tag