Post mortem changes Flashcards
before death
ante mortem
moment of death
agonal period or peri mortem
after death
post mortem
What are the three questions that should be answered in an autopsy?
- time of death?
- cause of death?
- maner of death?
Name four types of death?
- cellular death
- somatic death
- clinical death
- “apparent death” suspended animation
What is cellular death?
- due to lack of oxygen and blood
- cells don’t longer
- function
- have metabolic activity
- aerobic respiration
- different tissues die at different rates
When do different tissues die?
- cerebral cortex/neurons: within minutes
- white blood cells: within hours
- connective tissue and muscle cells: within days
What is somatic death?
- the body loses its sentinent personality, i.e. doesn’t perceive or feel
- unconscious
- reflex activity is intact
- cardiorespiratory function is intact
What is clinical death?
permanent cessation of cardiovascular, respiratory and brain functions
Name early changes occuring with death
(6)
- 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
Name some post mortal processes
(5)
- no glucose and oxygen –> ATP is consumed
- cellular homeostasis cease
- autlysis by cellular enzymes
- bacteria spread from the bowl
- insects and animals scavenger
Name some chemical changes occuring with death
(5)
- 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
Due to which conditions occurs a state that may mimic death?
(6)
- head injury
- hypothermia
- sun or heat stroke
- drowning
- drug overdose
- electrocution
Name five early signs of death
- 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)
What are the three classical signs for certain death?
- livor
- rigor
- algor
Name changes in the eye occuring with death
- 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
Name changes in the skin occuring with death
- loss of translucency
- pale and ashy white appearance - pallor mortis
- loss of elasticity
Livor mortis facts
- 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
Colour of hypostasis/livor mortis that indicates mode of death
cherry-pink
carbon monoxide poisoning
Colour of hypostasis/livor mortis that indicates mode of death
dark blue-scarlet
cyanide poisoning
Colour of hypostasis/livor mortis that indicates mode of death
brown
methahemoglobinemia
Colour of hypostasis/livor mortis that indicates mode of death
bronze
septic abortion caused by clostridium perfringes
Colour of hypostasis/livor mortis that indicates mode of death
pallor
anemia, hemorrhage
Colour of hypostasis/livor mortis that indicates mode of death
pink around large joints
hypothermia
Differences in livor mortis and contusion in respect to:
- borders
- colour
- blanching
- hemorrhage
- 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
what are vibices
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
What are petechial hemorrhages?
- 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)
What is the forensic importance of hypostasis/livor mortis?
(5)
- 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
Name post mortem changes in the muscle
- primary relaxation/flaccidity
- rigor mortis (cadaveric rigidity)
- secondary relaxation
Name characteristics of primary relaxation
(5)
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
What are the chemical changes underlying rigor mortis?
- 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
Name three causes of rigor mortis
- ATP depetion
- actin-myosin interaction
- lactic acid accumulation
Estimated time of death from rigor mortis
in face
1-4 hours
Estimated time of death from rigor mortis
limbs
4-6 hours
Estimated time of death from rigor mortis
increase in strenght for the next ….
6-12 hours
Estimated time of death from rigor mortis
re-establishment possible
2-8hours
Estimated time of death from rigor mortis
complete rigor
10-12 hours (2-20)
Estimated time of death from rigor mortis
decomposition starts –> secondary flaccidity
24-72 hours
Name three factors that affect the timing of rigor mortis
- muscular activity before death
- environmental temperature
- age
How does muscular activity before death affect rigor mortis?
- 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
How does environmental temperature affect rigor mortis?
- cold and dry air –> onset slow, duration longer
- warm and moist air –> onset fast, duration shorter
How does age affect rigor mortis?
- infants and elderly –> rapid onset
Conditions mistaken for rigor mortis
- heat stiffness
- cold stiffness
- cadaveric spasm / instantaneous rigor
Forensic implications of rigor mortis
- reliable sign of death
- time since death can roughly b estimated
- indicates body position at death
What is the rate of body cooling in algor mortis?
1 degree C per hour during the first 24 hours
Times until a naked body reaches ambient temperature
- a normal sized body
- a thin body
- an obese body
- approx 28-30 hours
- approx 20 hours
- apporx 40-50 hours
Name five factors that affect the rate of cooling
- conditions in which heat may be retained or increased
- surface area of the body
- environmental temperature
- water
- clothing, coverings and posture
How do conditions in which heat may be retained or increased affect the cooling rate of the body?
- 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
How does the surface area afffect the rate of cooling of the body?
larger surface area –> speeds up cooling rate
How does the environmental condition affect the cooling rate of the body?
- higher humidity: rapid cooling rate
- rapid air velocity: rapid cooling rate
How does water affect the cooling rate?
rapid cooling rate, more rapid in flowing water than still water
Rules of thumb for post mortem interval
- warm and flaccid body
- warm and stiff body
- cold and stiff body
- cold and flaccid body
- < 3 hours
- 3-8 hours
- 8-36 hours
- >36 hours
Name some late signs of death
(5)
- decomposition/putrefaction (decay)
- adipocere formation
- mummification
- putrid dry remains
- skeletonisation
What is post mortem decomposition
Turning the tissue of the body into fluids and gases by the effect of bacteria and enzymes
Name two mechanisms leading to decay
- 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
Name morphological changes of putrefaction
- 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
What does the speed of decomposition depend on?
- amount of bacteria in the body
- temperature (heat –> rapid)
- humidity (high –> rapid)
- injuries to body surface (promote putrefaction)
What influences the microbial, insect and animal activity on the dead body?
- 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
Forensic importance of mummification
(3)
- identification, could retain natural appearance and features of the body
- time since death can roughly be estimated
- can detect abnormal pathology inside deep organs
what are the chemical causes for adipocere and what are the optimal conditions for the formation of adipocere?
- chemical causes:
- hydrolysis
- hydrogenation
- conditions
- moisture
- warm environment
Forensic importance of adipocere (3)
- 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
What are putrid dry remains?
- the body continues to lose more soft tissue, and the process of skeletonisation begins
- bones, tendons, hair and fingernails remain
- still smell of decay
Forensic importance of skeletonisation
- identification
- may give conclusions about age, sex and stature
- estimating time since death (e.g. carbon-14 dating)
