forensic science hair
Human hair generally has a medullary index of less than __________; the hair of most animals has an index of __________ or greater.
1/3 1/2
Microscopic hair comparisons must be regarded by police and courts as presumptive in nature, and all positive microscopic hair comparisons must be confirmed by ________ typing
DNA
neutron activation analysis can check hair for the presence of
DNA
hair is composed of a protein called cellulose
False (keratin)
Why is hair considered class evidence?
It cannot be traced back to a single person unless you don't have the root which has the DNA
catagen stage
Transition stage of hair growth
which of the following is most likely a result of hair bleaching?
a yellowish tint to the hair
explain how the police can determine if the woman has been off drugs for over one year
drug substances can be found in the scalp
Cuticular scale patterns in human head hairs tend to be very regular.
false
Hair continuously grows all along its shaft.
false
all hairs on the head of a person are identical
false
describe the structure of hair. include in your answer the terms follicle, medulla, cortex, and cuticle
follicle: actively growing root or base of a hair containing DNA and living cells medulla: spongy, central, interior core of hair that gives it flexibility; appears as a canal in the middle of the shaft cortex: thickest layer, most pigment, denser near cuticle cuticle: outermost layer, overlapping scales, has different shapes
continuous medulla
found mainly in animals
Hair is individualizable evidence when...
hair evidence is not individualizable
Hair is an appendage of the skin, growing out of an organ known as the _____.
hair follicle
human hair has which type of cuticle?
imbricate
which of the following is an advantage of drug testing using hair rather than urine?
it gives a short-term drug use history
The central canal running through many hairs is known as the:
medulla
The hair shaft is composed of the cuticle, cortex, and
medulla
The diameter of the medulla relative to the diameter of the hair shaft is the ___
medullary index
which is true about DNA typing of hair?
only mitochondrial DNA typing is commonly done on human hair
____ hairs are short and curly, with one wide variation in its shaft diameter
pubic
anagen stage
rapid growth stage of hair
Which part(s) of a hair can be analyzed for DNA?
root
which of the following is NOT a layer of hair?
root
which of the following is NOT found in the cortex?
scales
assuming the hair grows at the rate of .44mm per day, on approximately what date did the woman die?
she died on august 19, 2004 - 8/.44=18.18
cortical fusi
small cells located in cortex
which of the following is NOT a type of medulla found in a human hair?
stacked
Although variations can occur, which of the following best describes northern European hair?
straight with evenly distributed granules
If a hair falls out on its own, without any combing or pulling, it is likely in which growth stage?
telogen
describe two ways that animal hair differs from human hair
the animal medulla is much thicker than humans' and human hair is denser toward the cuticle than animals'
which factors are used to calculate the medullary index of the hair?
width of cortex and the width of the medulla
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 hair?
58/110=.5272 -animal -animal hair is .50 or more, human hair is .30 or less
cortex
Middle layer of the hair
in which of the following growth stages of hair does active growing take place?
anagen
the period of active hair growth is called the _____ stage
anagen
Three stages of hair growth
anagen, catagen, telogen
A hair with a thick cuticle and regular scales and a continuous medulla is...
animal other than human
why is it important that the police pull the hairs from her head rather than cut her hair?
bc they need the follicle since it has DNA
why does the hair being found at the scene and of the woman's not necessarily prove that she was the guilty party?
because she could've been at the same place as well but as a guest/customer/whatever the circumstance
the ___ contains the pigment granules that impart color to hair
cortex
The three layers of the hair shaft are the ___, the ___, and the ___.
cuticle cortex medulla
which of the following characteristics is found in typical Asian hair?
dark medulla
melanin
the substance that gives skin its color
if a known and unknown hair have very similar microscopic characteristics and no unexplainable differences, then:
the unknown could have come from the known source
why is it necessary to obtain 25 or 50 hairs from this woman?
they need to get all the areas of the scalp
the cuticle scales of the hair always point toward the
tip of the hair
The cortex may contain pigment granules
true
the average lifetime of head hair is about three months
true
the shaft of the hair is considered class evidence in a trial.
true
there are three stages of growth in hair
true
