Decomposition Flashcards
What is decomposition?
A process that begins at death, involving loss of soft tissue and skeletonisation
What are the 6 stages of decomposition?
- Fresh
- Initial decay - bloating
- Putrefaction
- Black putrefaction
- Buytric fermentation
- Dry decay
List these organs in the order they decompose:
1. kidneys
2. stomach
3. lungs
4. blood
- Intestines, STOMACH, digestion organs, heart & BLOOD
- Air passages & LUNGS
- KIDNEYS & bladder
- Brain & nervous tissue
- Skeletal muscle
- Connective tissue & integument
- Bones
What is autolysis and what causes it?
Cellular self-destruction, caused by lack of oxygen
Describe what happens in autolysis.
- Hydrolytic enzymes release into cytoplasm
- Digest proteins and carbs
- Carbon dioxide decreases pH of cell cytoplasm
- Nutrient-rich fluid released into interstitial space
What factor influences autolysis?
Temperature
How does autolysis allow putrefaction to start?
By creating an anaerobic environment due to carbohydrate release
In putrefaction, what is soft tissue broken down into? By what?
- gases, liquids and salts
- Anaerobic bacterial activity
What is the result of diagenesis?
Loss of organic components
Dissolution of mineral compounds
What does bacteria continue to do after decomposition slows after skeletonisation?
Remove collagen from bone
At what point does bone diagenesis stop?
When chemical equilibrium is met between soil/water and the bone
What factors affect the rate of diagenesis cessation?
Environment
Time
List the signs of putrefaction.
- Discolouration
- Dissolution
- Distension
- Degradation
List biotic factors of decomposition.
- Animal scavenging
- Insect activity
- Human interaction/intervention
What areas of a body are insects most drawn to?
Orifices and eyes
What is the impact on decomposition when the number of larvae present increase?
Rate of decomposition increases
How does animal scavenging both increase and decrease decomposition rate?
Increase: Feed on remains
Decrease: Feed on insects
What is the main characteristic of rodent gnawing on bone?
Parallel sets of striations
What areas are targeted by rodents?
Distal extremities and soft areas of the face
What is the typical order of body areas scavenged?
- Face and neck
- Thorax (heart and lungs)
- Upper extremities
- Lower extremities
- Trunk
What are the abiotic components associated with climate?
- Heat
- Cold
- Wind
What are the abiotic components associated with habitat?
- Soil
- Water
- Sand
As temperature decreases, what would you expect to happen to decomposition?
Decreased reaction rate so decreased decomposition rate
What can affect the temperature of human remains?
- Larval mass
- Clothing
- Wrappings
- Time since death
What would you expect in both low and high temperatures when the humidity is high?
Low: Slowing of decomposition
High: Rapid increase in decomposition
What would you expect in both low and high temperatures when the humidity is low?
Low: Arrest ( freeze drying)
High: Arrest (dehydration/mummification)
How does rainfall or a body of water slow decomposition?
Production of adipocere
Other than slowing decompostion, how else does rainfall impact remains?
Acts as a means of transport or depostion
What factors can move remains or change their position?
Snow
Water
Gravity
List the ground substrates in order of most draining to least:
Clay soil
Sandy soil
Organic soil
Sand
Clay
- Sand
- Sandy soil
- Organic soil
4.Clay soil - Clay
Name the mortices in order of when they happen.
- Livor mortis
- Algor mortis
- Rigor mortis
Briefly describe what happens in livor mortis.
Settling of blood cells due to gravity, causing coagulation of blood
How can livor mortis be used in a forensic investigation?
Blood fixing can indicate positioning as well as objects around remains
Briefly describe what happens in algor mortis.
Change in temperature to match the temperature of the environment
True or False: The body cools by about 1 degree Celsius per hour for the first 24 hours.
False, 1 degree Celsius per hour for the first 12 hours
What impacts the rate of algor mortis?
Temperature gradient between environment and body
Briefly describe what happens in rigor mortis.
Gradual stiffening of muscles
Why does rigor mortis happen?
Muscle contractions caused by a build up of ATP
What is marbling?
Progressive discolouration of the body with dark tracks
What causes marbling?
Progress of sulfhaemoglobin through the vascular system
Where is marbling typically first observed and what does it usually accompany?
- Upper right quadrant of abdominal region (by gallbladder)
- Start of abdominal bloating
What is skin blistering a result of?
Separation of outer layers of epidermis from underlying skin layers
What is the name of the process of blistered skin sloughing off?
Degloving
What causes bloating of cavities?
Production of decompositional gases
Name 2 examples of volatile organic compounds (VOCs).
- Putrescine
- Cadaverine
What is saponification?
Process of adipocere formation from body fat hydrolysis
True or False: Saponification forms an anaerobic environment on the soft tissue of remains.
True
When is saponification observed?
In remains that are exposed to bodies of water after a period of time
How does mummification reduce/arrest decomposition rate?
Removes water access for bacteria
How does freezing reduce/arrest decomposition rate?
Dries tissue, resulting in tissue preservation
