Chapter 3 Hair Analysis

Class Evidence

tell what kind of group it comes from

Comparison Microscope

a compound microscope that allows the side-by-side comparison of samples

Cortex

the region of hair located outside the medulla containing granules of pigment

Hair Follicle

the actively growing root of the hair that contains DNA and living cells

Individual Evidence

a kind of evidence that identifies a particular person or thing

Keratin

a type of fibrous protein that makes up the majority of the cortex of a hair

Medulla

the central core of a hair

Melanin Granules

bits of pigment found in the cortex of a hair

Neutron Activation Analysis

a method of analysis that determines the composition of elements in a sample

Trace Evidence

small but measurable amounts of physical or biological material found at a crime scene

Secondary Transfer

when material is moved from one place to another by adhering to clothing or other materials

Evidence hair can provide

racial background; use of drugs, toxins, and the presence of heavy metals; to the assessment of nutritional deficiencies; if follicle is present DNA evidence can be used to identify individuals

Function of Hair

regulates body temperature, decreases friction, protects against sunlight

a folicle embeded in the skin

What produces the hair shaft?

the protein keratin

What is the shaft made of?

Follicle

club shape at the base of the hair

Papilla

blood vessels that feed the hair so it can grow

Sebacious Gland

secretes oil to condition hair

nerves and an erector muscle

What attach so the hair can respond to the enviroment?

Cuticle

transparent outermost layer of the hair

Imbrication

overlapping scales that protect the inner layers

Cortex

thickest layer, contians most of the pigment granules, distribution of pigment varies, usually denser nearer the cuticle

Medulla

center of the hair, can be a hollow tube or filled with cells, some people lack this part of the hair, others may be fragmented or segmented, other may have a double medulla

Continuous Medulla

one unbroken line of color

Interrupted Medulla

pigmented line broken at regular intervals

Fragmented Medulla

pigmented line unevenly spaced

Solid Medulla

pigmented areas filling both the medulla and the cortex

blunt, buckled, double medulla

Types of hair

Cross Section

circular, triangular, irregular, or flattened; shape influences the curl of the hair; coarse or fine texture

Anagen -> Catagen -> Telogen

Life Cycle of Hair

Anagen

lasts 1000 days, 80-90% of all human hair actively grows, cells around the folicle rapidly divide and deposit materials in the hair

Catagen

2% of all hair growth and development, hair grows and changes

Telogen

10-18%, follicle becomes dormant