Morphology – refers to form and structure Chapter 5 Hair Hair and fingernails really don’t continue to grow after death, the scalp and tissue shrinks giving the appearance of growth. Morphology – refers to form and structure

Hair shaft is composed of 3 parts: cuticle, cortex and the medulla

Cuticle – tough, clear outside covering of the hair shaft, covered in fine scales that always point toward the tip end of each hair. Scales – specialized cells on the cuticle that are hardened (keratinized) and overlap.

Cortex – middle layer of the hair shaft that provides strength, comprises most of the hair mass, show the color of the hair under the microscope. Melanin - the pigment of hair, spindle-shaped cortical cells. Gives hair its shape

Medulla – the spongy interior core of the hair that gives it flexibility appears as a canal in the middle of the shaft. Medulla of animal is very fat, almost to the cuticle, very little cortex layer.

keratin A tough protein polymer made up a of about 20 different amino acids. The principal one is cysteine, which allows resistant to chemical and biological degradation.

4 types of medulla. Absent – no medulla, damaged hair 4 types of medulla Absent – no medulla, damaged hair Fragmented – very small amounts, dots Interrupted – small amounts of medulla missing Continuous – straight line, no amounts missing

Animal Hair Notice that animal hair has larger medulla’s than human hair Stacked medulla – cat hair Continuous medulla

3 stages of growth Anagen phase – averaging 3 -5 years, Active period of growth in the hair cycle Catagen phase – intermediate period of growth, lasting about 3 weeks, hair has finished growing. Telogen phase – final phase – resulting n the loss of hair over about 3 months.

What can be learned from hair Human or animal Body area of origin Cut, shed or forcibly removed Disease Comparison to known samples (id)

What Can NOT be learned from hair Age Gender Natural hair color race

Was the hair cut, shed or forcibly removed?

Terms for Hair Buckling – appearance of caving in of the hair. What causes this? Heat styling wet or damp hair causes the water in the hair to explode out in little moisture bursts. This causes a buckling and bubbling effect on the hair cuticle along the entire length of your hair, and has the appearance of a blister when you look at it closely.

Distal end – end of hair that is furthest from the root. Hair – any fine, cylindrically shaped fiber growing from skin of mammals. Medial region (middle) – portion of hair between proximal and distal ends.

Medulla – anatomic region of a hair normally located in the center of the cortex. Melanin – pigment that provides the color to the hair. Proximal end – end of the hair nearest the root end.

Facts Hair is an outgrowth of the epidermis. Epidermis is the outer layer of the skin. Follicles are the structures from which hair originate and grow. When hair reaches the top of the skin, the outer layer begins to harden into keratin (this makes up fingernails and toenails in humans and horns in other animals)

Anything that is ingested by the person, such as food, drugs, or poisons, will eventually be incorporated into the growing region of the hair. When the hair reaches the surface of the skin and keratinizes, it is essentially dead. When hair grows, it is really being “pushed up” by the growing part of the hair in the follicle. Head hair grows approximately ½ inch per month. This can be used to estimate the time when a drug or other substance was ingested. Normally, a person will naturally shed a few dozen hairs per day. It takes about 6 months to completely regrow a scalp hair. DNA can be taken from the root of hair.

Forcible Removal of Hair Forcibly removed hair will have follicle cells clinging to the hair. Some may actually have blood on the root.

Hair color Melanin – is the pigment that gives hair its color. There are 2 types of melanin: dark brown and blond. Melanin does not take up the dye, instead the dye coats the surface of the hair.

Chapter 6 Fibers Fibers – usually made up of many filament twisted or bonded together to form a thread or yarn, considered class evidence. 2 types: Natural Man-made

To identify use microscope for comparison for color and diameter. Yarn - continuous strand of fibers, Blend – a fabric made up of two or more different types of fiber,

3 types of fibers