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Forensic Genetics and Medicine > Post mortem changes > Flashcards

Post mortem changes Flashcards

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1
Q

before death

A

ante mortem

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2
Q

moment of death

A

agonal period or peri mortem

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3
Q

after death

A

post mortem

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4
Q

What are the three questions that should be answered in an autopsy?

A
  • time of death?
  • cause of death?
  • maner of death?
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5
Q

Name four types of death?

A
  • cellular death
  • somatic death
  • clinical death
  • “apparent death” suspended animation
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6
Q

What is cellular death?

A
  • due to lack of oxygen and blood
  • cells don’t longer
    • function
    • have metabolic activity
    • aerobic respiration
  • different tissues die at different rates
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7
Q

When do different tissues die?

A
  • cerebral cortex/neurons: within minutes
  • white blood cells: within hours
  • connective tissue and muscle cells: within days
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8
Q

What is somatic death?

A
  • the body loses its sentinent personality, i.e. doesn’t perceive or feel
  • unconscious
  • reflex activity is intact
  • cardiorespiratory function is intact
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9
Q

What is clinical death?

A

permanent cessation of cardiovascular, respiratory and brain functions

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10
Q

Name early changes occuring with death

(6)

A
  • loss of all reflexes
  • no reaction to painful stimuli
  • muscular flaccidity, complete loss of tone
  • cessation of heart beat (cardiac death/arrest) and respiratory movements
  • eye signs: loss of corneal and light reflexes, fixed dilated pupils, eyelids usually closed incompletely
  • pallor mortis, 15-120 minutes after death
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11
Q

Name some post mortal processes

(5)

A
  • no glucose and oxygen –> ATP is consumed
  • cellular homeostasis cease
  • autlysis by cellular enzymes
  • bacteria spread from the bowl
  • insects and animals scavenger
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12
Q

Name some chemical changes occuring with death

(5)

A
  • glucose is consumed rapidly –> produces lactate
  • potassium leaks from the cell
  • enzymes and bacteria denature proteins
  • fat: solid to fluid
  • DNA is stable for a long time
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13
Q

Due to which conditions occurs a state that may mimic death?

(6)

A
  • head injury
  • hypothermia
  • sun or heat stroke
  • drowning
  • drug overdose
  • electrocution
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14
Q

Name five early signs of death

A
  • changes in the eye
  • changes in the skin, pallor mortis
  • livor mortis (post mortem lividity/hypostasis)
  • rigor mortis (cadaveric rigidity)
  • allgor mortis (cooling of the body)
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15
Q

What are the three classical signs for certain death?

A
  • livor
  • rigor
  • algor
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16
Q

Name changes in the eye occuring with death

A
  • corneal changes
    • loss of clear glistening
    • dry, cloudy and opaque
    • loss of reflexes
  • intraocular tension falls, eye balls become flaccid and sink in the orbit
  • pupils fully dilated in the early stage and constrict later due to rigor mortis
  • brownish discolouration of the sclera due to cellular debris and dust
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17
Q

Name changes in the skin occuring with death

A
  • loss of translucency
  • pale and ashy white appearance - pallor mortis
  • loss of elasticity
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18
Q

Livor mortis facts

A
  • gravity moves blood after circulation stopps
  • blood accumulates in the capillaries –> purple or reddish purple
  • in pressure areas –> pale
  • apparent after 0,5-1 hour
  • fixed after approx 8 hours
  • may not appear at all especially in infants, elderly, and anemic persons
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19
Q

Colour of hypostasis/livor mortis that indicates mode of death

cherry-pink

A

carbon monoxide poisoning

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20
Q

Colour of hypostasis/livor mortis that indicates mode of death

dark blue-scarlet

A

cyanide poisoning

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21
Q

Colour of hypostasis/livor mortis that indicates mode of death

brown

A

methahemoglobinemia

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22
Q

Colour of hypostasis/livor mortis that indicates mode of death

bronze

A

septic abortion caused by clostridium perfringes

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23
Q

Colour of hypostasis/livor mortis that indicates mode of death

pallor

A

anemia, hemorrhage

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24
Q

Colour of hypostasis/livor mortis that indicates mode of death

pink around large joints

A

hypothermia

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25
Q

Differences in livor mortis and contusion in respect to:

  • borders
  • colour
  • blanching
  • hemorrhage
A
  • borders:
    • livor: diffuse
    • contusions: distinct
  • colour:
    • livor: purple to red
    • contusion: purple to blue
  • blanching:
    • livor: present with fingure pressure
    • contusion: not present
  • hemorrhage:
    • livor: none
    • contusion: in soft tissue
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26
Q

what are vibices

A

post morte eccymoses, death spots (subcutaneous spots of bleedings)

  • limited to area of livor mortis
  • only occurs post mortem
  • due to increase in intravascular pressure that leads to mechanic rupture of subcutaneous capillaries and smaller vessels
27
Q

What are petechial hemorrhages?

A
  • rupture of capillaries due to hydrostatic pressure that causes small areas of skin hemorrhaging
  • dark, circular spots ranging in size from pin-point to max 3mm
  • in the sclera of the eye and the face suggest asphyxation (suffocation, strangulation)
28
Q

What is the forensic importance of hypostasis/livor mortis?

(5)

A
  • reliable sign of death
  • colour may suggest the cause of death
  • time since death can be estimated
  • it gives information about the position of the body at the time of death
  • indicates if the body was moved or not after death and could give information about the manner of death
29
Q

Name post mortem changes in the muscle

A
  • primary relaxation/flaccidity
  • rigor mortis (cadaveric rigidity)
  • secondary relaxation
30
Q

Name characteristics of primary relaxation

(5)

A

Starts immediately after death

  • drop of lower jaw
  • eye balls lose their tension
  • pupils are dilated
  • joints are flaccid
  • smooth muscle cells relaxation –> incontinence of urine and faeces
31
Q

What are the chemical changes underlying rigor mortis?

A
  • death
  • cessation of respiration
  • depletion of oxygen used in the making of ATP
  • ATP no longer provided to operate the SERCA pumps in the membrane of the SR, which pump calcium ions into the termincal cisternae
  • calcium ions diffuse from the terminal cisternae and extracellular fluid to the sarcomere
  • Ca binds with troponin
  • cross bridging between myosin and actin proteins
32
Q

Name three causes of rigor mortis

A
  • ATP depetion
  • actin-myosin interaction
  • lactic acid accumulation
33
Q

Estimated time of death from rigor mortis

in face

A

1-4 hours

34
Q

Estimated time of death from rigor mortis

limbs

A

4-6 hours

35
Q

Estimated time of death from rigor mortis

increase in strenght for the next ….

A

6-12 hours

36
Q

Estimated time of death from rigor mortis

re-establishment possible

A

2-8hours

37
Q

Estimated time of death from rigor mortis

complete rigor

A

10-12 hours (2-20)

38
Q

Estimated time of death from rigor mortis

decomposition starts –> secondary flaccidity

A

24-72 hours

39
Q

Name three factors that affect the timing of rigor mortis

A
  • muscular activity before death
  • environmental temperature
  • age
40
Q

How does muscular activity before death affect rigor mortis?

A
  • healthy and robust muscle at rest –> slow onset, duration longer
  • muscles exhausted/fatigued –> onset rapid, especially in those limbs being used
  • increased activity (convulsions, electrocution, lightning) –> rapid onset and short duration
41
Q

How does environmental temperature affect rigor mortis?

A
  • cold and dry air –> onset slow, duration longer
  • warm and moist air –> onset fast, duration shorter
42
Q

How does age affect rigor mortis?

A
  • infants and elderly –> rapid onset
43
Q

Conditions mistaken for rigor mortis

A
  • heat stiffness
  • cold stiffness
  • cadaveric spasm / instantaneous rigor
44
Q

Forensic implications of rigor mortis

A
  • reliable sign of death
  • time since death can roughly b estimated
  • indicates body position at death
45
Q

What is the rate of body cooling in algor mortis?

A

1 degree C per hour during the first 24 hours

46
Q

Times until a naked body reaches ambient temperature

  • a normal sized body
  • a thin body
  • an obese body
A
  • approx 28-30 hours
  • approx 20 hours
  • apporx 40-50 hours
47
Q

Name five factors that affect the rate of cooling

A
  • conditions in which heat may be retained or increased
  • surface area of the body
  • environmental temperature
  • water
  • clothing, coverings and posture
48
Q

How do conditions in which heat may be retained or increased affect the cooling rate of the body?

A
  • sun or heat stroke and pontine (brain stem) hemorrhage disturbe the heat regulating mechanism
  • tetanus and strychnine poisoning, due to increase in heat production in the muscle
  • if there is a fulminating infection, the body temperature may continue to rise for some hours after death
49
Q

How does the surface area afffect the rate of cooling of the body?

A

larger surface area –> speeds up cooling rate

50
Q

How does the environmental condition affect the cooling rate of the body?

A
  • higher humidity: rapid cooling rate
  • rapid air velocity: rapid cooling rate
51
Q

How does water affect the cooling rate?

A

rapid cooling rate, more rapid in flowing water than still water

52
Q

Rules of thumb for post mortem interval

  • warm and flaccid body
  • warm and stiff body
  • cold and stiff body
  • cold and flaccid body
A
  • < 3 hours
  • 3-8 hours
  • 8-36 hours
  • >36 hours
53
Q

Name some late signs of death

(5)

A
  • decomposition/putrefaction (decay)
  • adipocere formation
  • mummification
  • putrid dry remains
  • skeletonisation
54
Q

What is post mortem decomposition

A

Turning the tissue of the body into fluids and gases by the effect of bacteria and enzymes

55
Q

Name two mechanisms leading to decay

A
  • autolysis: occurs by digestive enzymes released from the cells after death
  • putrefaction: bacterial action (Clostridium welchii, Streptococci, E coli, B proteus)
    • most common route of decomposition
56
Q

Name morphological changes of putrefaction

A
  • green discolouration; 2 days
  • marbling of skin; 3-5 days
  • skin blisters, skin slippage (epidermolysis); 5-7 days
  • gas formation, swelling of body; 7-10 days
57
Q

What does the speed of decomposition depend on?

A
  • amount of bacteria in the body
  • temperature (heat –> rapid)
  • humidity (high –> rapid)
  • injuries to body surface (promote putrefaction)
58
Q

What influences the microbial, insect and animal activity on the dead body?

A
  • geographical location
  • time of year
  • exposure to sunlight
  • wrapping and confinement
  • burial (type of soil, burial dept)
  • haning above ground
  • burial under water
  • wounds
  • infections
  • burning
  • chemical treatment
59
Q

Forensic importance of mummification

(3)

A
  • identification, could retain natural appearance and features of the body
  • time since death can roughly be estimated
  • can detect abnormal pathology inside deep organs
60
Q

what are the chemical causes for adipocere and what are the optimal conditions for the formation of adipocere?

A
  • chemical causes:
    • hydrolysis
    • hydrogenation
  • conditions
    • moisture
    • warm environment
61
Q

Forensic importance of adipocere (3)

A
  • preserve the body which can permit identification after death
  • it may give conclusions about the cause of death
  • it indicates that the time since death was at least weeks to several months
62
Q

What are putrid dry remains?

A
  • the body continues to lose more soft tissue, and the process of skeletonisation begins
  • bones, tendons, hair and fingernails remain
  • still smell of decay
63
Q

Forensic importance of skeletonisation

A
  • identification
  • may give conclusions about age, sex and stature
  • estimating time since death (e.g. carbon-14 dating)

Forensic Genetics and Medicine (19 decks)

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