unit 8: death, entomology, and anthropology Flashcards
cause of death:
the injury or condition responsible for a person’s death
ex. disease, injury, stroke, poisoning, or heart attack
mechanism of death:
the specific psychological, physical, or chemical event that stops life
ex. blood loss, loss of oxygen (asphyxiation)
manner of death definition:
determination of how injury or disease leads to death
manners of death:
- natural
-> interruption and failure of body functions resulting from age or disease - accidental
-> death caused by unplanned events - suicidal
-> death caused by oneself - homicidal
-> the death of one person intentionally caused by another person - undetermined
body changes after death:
- heart stops
-> blood is no longer pumping
-> stops delivery of oxygen and glucose - cells produce less energy
->lack of oxygen and glucose leads to less energy available for cells - anaerobic respiration
-> less energy is produced and lactic acid builds up - cells rupture
-> toxic wastes accumulate
-> cell membranes rupture and cytoplasm seeps out of cells
autolysis:
cellular enzymes are released inside the cell that break down the cell contents and rupture the cell membrane, destroying the cell
PMI:
post mortem interval
TOD:
time of death
Algor Mortis
-> the cooling of the body after death
-> temperature of body can be used to determine post mortem interval
-> temperature should be taken from the liver or rectum
-> body will lose heat to surroundings until it reaches ambient temperature
-> body cools at a rate of 1.4 F per hour for the first 12 hours
-> 0.7 F per hour after
Livor Mortis
-> lividity becomes visible appx. 2 hours after death and becomes permanent after 8 hours
-> results from gravity and can reveal position of body during first 8 hours after death
lividity:
the reddish-purple color that results after break down of blood vessels and release of hemoglobin
Rigor Mortis:
-> death stiffness
-> in order for muscles to relax, calcium is released, without oxygen and the production of energy a person in the process of death cannot relax their muscles
-> muscles will become rigid within 2 hours of death
-> muscles will then relax after autolysis of cells, appx. 48 hours after death
factors to consider when determining PMI:
-> a person’s body mass relative to surface area (weight)
-> body position
-> clothing on the body
-> environment/ambient temperature
-> level of physical activity
-> autopsy
autopsy:
medical examination to determine the cause and manner of death
clinical autopsy:
performed for medical research purposes when foul play is not considered
ex. a person in good health dies unexpectedly
forensic autopsy:
performed when foul play is suspected
-> state laws vary regarding when an autopsy is required
-> all states require autopsies for deaths due to injuries, poisoning, unusual infections, and foul play
-> suspicious deaths are reported to the coroner or medical examiner that determines if an autopsy is needed
-> an external and internal examination is performed and documented
stomach and intestinal contents:
-> 2-6 hours for the stomach to empty its contents
-> 12 hours for the food to leave. the small intestine
-> 24 hours from time of meal was eaten until waste is eliminated through the rectum
postmortem changes in the eye:
-> potassium builds up in the eye leading to a cloudy film
-> film is observed within 2-3 hours if the eye is open
-> observed within 24 hours if the eye is closed
-> buildup of potassium could be used to estimate TOD, this method is not considered reliable yet
stages of decomposition:
- several hours after death
- after several days
- days 7-23
- after 3 weeks to 2 months
- after 2 months
stage of decomposition: several hours after death
-> cell autolysis
-> loss of muscle tone
-> bladder and rectum empty
-> onset of algor, livor, and rigor mortis
-> cloudy film forms over the eyes
-> flies arrive to deposit eggs on body
stage of decomposition: after several days
-> blistering of skin and internal organs results in skin slippage
-> putrefaction begins (destruction of soft tissues due to bacteria)
-> abdominal swelling due to release of CO2 from anaerobic respiration
-> marbling of skin occurs
-> internal pressure from fluids may force fluids from body openings
-> loss of rigor mortis
-> increased insect activity
stage of decomposition: days 7-23
-> bloating continues as more gases are released from the body
-> discoloration of skin may make ID of skin color impossible
-> ruptures in skin occur- more seepage of fluid- increased bacterial and insect activity
-> soft tissues start to liquify
stage of decomposition: after 3 weeks to 2 months
-> greatest loss of mass due to insect infestation, bacterial action, and purging of fluids
->fats start to decompose forming greasy wax or adipocere
-> adipocere prevents oxygen from reaching underlying tissues which can preserve tissue
stage of decomposition: after 2 months
-> soft tissues are usually done
-> bones remain
-> odors are mostly gone
entomology:
the study of insects and other arthropods (spiders)
forensic entomology:
- interpretation of that insect evidence in criminal and civil investigations
- provides an estimate of min and max time that could’ve passed since colonization (of the insects)
what are the forms insect evidence can be found in?
- adults
- pupae
- larvae
- eggs
- insect body parts
general decomposition stages:
- fresh (2 days)- warm, newly dead body
- bloated (1 week)- a corpse emits odors of decaying flesh
- decay- a body emits gases of decay with strong odors, and shows signs of darkened tissues
- dry/skeletal decay- mostly bones remain
bacteria produces two gases:
putrescine and cadaverine
Blowfly life cycle: <8 hours after death
blowfly eggs found in moist, warm area of corpseshour
Blowfly life cycle: within 20 hours after death
1st of the 3 larva stages
Blowfly life cycle: 4-5 days after death
3rd of the larva stage
Blowfly life cycle: 8-12 days after death
larvae migrates to dry places
Blowfly life cycle: 18-24 days after death
early pupa; changes from light brown to dark brown; immobile
Blowfly life cycle: 21-24 days after death
pupa case splits open and adult blowfly emerges
insects can help to determine ___.
postmortem interval
environmental conditions that impact insect growth:
- temperatures
- time of day (egg laying doesn’t happen at night)
- rainfall/precipitation
two collections of evidence:
- collect live insects
- preserve other insects at scene
collect ___ first. collect ___ and ___ second
adults; larvae and eggs
after the body is removed, you should collect insects from ______
surrounding soil
what else can affect timing/development of insect life cycles
certain drugs; makes TOD analysis more difficult
___ drug speeds up development and ___ drug slows down development
cocaine; arsenic
what are bones?
framework for our body, anchor our muscles, allow movement, and protects vital organs
bones contain what along with living bone cells?
calcium and phosphate
infants are born with ___ bones that fuse into the ___ bones in an adult body
270; 206
ossification:
the process of bones replacing cartilage
ossification begins before ___ and continues for more than __ years
birth; 50
during childhood bones thicken, ___, and grow longer
ossify
after age __, bones lose ___ faster than they are built
30; minerals
what do bones contain?
“diary of injuries, disease, and nutritional deficiencies
what diseases are easily observed in bones?
osteoarthritis and osteopreosis
what is rickets caused by?
lack of vitamin D resulting in bowel legs, thinner skull, and deformed spine
what is anemia caused by?
lack of iron results in holes in the eye socket and skull
breaks that occur in advanced stages of decomposition snap off ___
easily
what is present in bones and can be tested?
different isotopes
what dissolved element is found in groundwater?
strontium
after ingestion, strontium is deposited in ___
teeth
food contains different amounts of stable ___ and ___
carbon-13 and carbon-12
after ingestion, these isotopes are absorbed into the ___
bone
male differences:
- frontal bone is low and sloping
- eye orbits are more square
- lower jaw (mandible) has an angle closer to 90˙
- pelvic cavity is heart shaped
- sacrum curves inward
female differences:
- the subpubic angle is greater than 90˙
- female pelvic cavity is oval shaped
- shorter tailbone
- sacrum curves outward
age can be determined by what?
- number of bones
- degree of ossification
- presence or absence of growth plates
- degree of wear on bones
- teeth
- skull sutures
it is difficult to determine ___ from skeletal remains
ancestry
prognathism:
projection of maxilla and/or mandible beyond the face
