forensic science chapter 3

human hair has which type of cuticle?

A. imbricate

which of the following is most likely a result of hair bleaching?

B. a yellowish tint to the hair

The cortex may contain pigment granules

true

Calculate the medullary index of a hair whose diameter is 110 microns wide and whose medulla measures 58 microns. Is this a human or animal?

58/110= .53. this is an animal hair

the body of a woman was found in the woods. Some hair fibers found on the body were sent to the crime lab for analysis. The ends of the hair attached to the body were gray, but the tips of the hair showed that it had been dyed. The distance from the root of the hair to the beginning of the dyed area measured 8 mm. Investigators determined the victim's hair had last been dyed on August 1, 2004. Assuming the hair grows at the rate of .44 mm per day, on approximately what date did the woman die? Explain your answer.

8/.44= 18 days after she dyed her hair.

which of the following characteristics is found in typical Asian hair?

A. dark medulla; only Asians have true black hair

the hair shaft is composed of the cuticle, cortex, and

A. medulla

Which part of a hair can be analyzed for DNA?

A. root

neutron activation analysis can check hair for the presence of?

A. silver

Although variations can occur, which of the following best describes northern European hair?

B. straight with evenly distributed granules

the period of active hair growth is called the..... stage?

C. anagen

the cuticle scales of the hair always point toward the?

C. tip of the hair

Contrast the appearance of hair coming from a person of European, Asian or African background.

European hair-tends to appear as generally wavy or straight. Asian hair-tends to appear straight. African hair-tends to be kinky, curly or coiled.

describe the structure of hair. Include in your answer the terms follicle, medulla, cortex, and cuticle?

Follicle- a club-shaped structure in the skin; at the end of a hair follicle is a network of blood vessels that supply nutrients to feed the hair and help it grow. The hair shaft is made up of three layers. An inner medulla, a cortex, and outer cuticle.

What is neutron activation analysis? Specifically, what would be the job of a neutron activation analyst be?

Neutron activation analysis is particularly useful technique that can identify up to 14 different elements in a single two-centimeter-long strand of human hair. The job of a neutron activation analyst would be to test and determine a timeline for when exposure to certain toxins or hair color might have occurred.

which factors are used to calculate the medullary index of the hair?

D. Medulla/ hair

All hairs on the head of a person are identical

false

hair is composed of a protein called cellulose

false; keratin

Briefly explain how goose bumps can form on someone.

hair works as a temperature regulator, when the outside temperature is cold, these muscles pull the hair strands up right, creating pockets that trap air. The air becomes trapped and heats you up.

A woman with long hair is suspected in a burglary case. At the crime scene, several long hairs were found attached to a broken long of the safe. The police obtain a warrant and request a sample of 25 to 50 hairs from this woman. They tell the woman it is important that they pull the hairs from her head rather than to merely cut the hairs. The police suspect that the woman was stealing to help support a drug habit.

a. why is it important that the police pull the hairs from her head rather than cut her hair? A-because the hair follicle is where the DNA can be found b. why is it necessary to obtain 25 to 50 hairs from this woman? B-because hair doesn't grow consistent or constant and 25 to 50 hairs gave a more accurate result/test c. the woman denies that she is currently taking drugs and states that she stopped using drugs a year ago. Explain how the police can determine if the women has been off drugs for over one year. C-the hair drug test can go back to 90 days d. suppose the hairs of the woman match the hairs found at the crime scene. Why does this not necessarily prove that she was the guilty party? D-this could be circumstantial evidence

why is hair considered class evidence?

because it can used to identify a special individual. In the best case, an investigator can identify a group or class of people who share simliar traits.

crime scene investigators collected hair from a dead person's body. One of the first things that needs to be established is if this hair is human or animal. Describe two ways that animal hair differs from human hair?

the pigmentation in human hair tends to be denser toward the cuticle, in animals it is denser toward the medulla. Animal pigments are often found in solid masses called ovoid bodies. Human hairs are usually one color along the length. Animal hairs can change color abruptly in a banded pattern. The medulla is much longer in animals(.50 or more medullary index), if the medullary index is .33 or less, the hair is from a human. Rodents and bats have a coronal cuticle with scales that give the appearance of a stack crowns. Cats, seals and mink have scales that are called spinous and resemble petals. Human hair has cuticle scales that are flattened and narrow, also called imbricate.

The shaft of the hair is considered class evidence in a trial

true