Stages and characteristics of Human Decomposition. Flashcards
What is decomposition?
- Decay which is caused by bacteria and fungi.
- A continual process that can take weeks, dependent on the environment.
- Reduction and break down of the body after death.
What is taphonomy?
- Means burial and law.
- The study of the processes of transition or organic life from the biosphere to the lithosphere.
- The process on how organisms decay.
What is the biosphere and the lithosphere?
- The biosphere is the components that make up the parts of the earth where organisms live.
- The lithosphere is the earth’s outer solid layer.
What does CDI mean?
- Cadaver decomposition island.
What is microbiome?
- The genetic material of microorganisms in a particular environment.
- Our own unique bacteria.
- When an organism dies microbiome is converted into necrobiome.
What is necrobiome?
- A community of species which is involved in the decay of remains after an organism has died.
Define forensic taphonomy and what it is.
- It is the study of the fate of human remains.
- What happens to a body between death and when remains have been discovered.
- PMI estimation.
Name the five stages of decomposition in order.
- Fresh
- Bloat
- Active decay
- Advanced decay
- Skeletonization
What happens during the FRESH stage of decomposition?
- Occurs up to 72 hours and algorithms, rigorously and liver mortis occurs.
What happens during the BLOAT stage of decomposition?
- Distension in the abdominal cavity and this is due to the build up of gases in the body.
What happens during the ACTIVE DECAY stage of decomposition?
- Insect activity occurs and maggots are active on the body.
What is the ADVANCED DECAY stage in decomposition?
-Insect activity starts to decrease and beetles remain, the drying of tissues occurs.
What is the SKELETONIZATION stage in decomposition?
- Dry remains.
How can decomposition be regulated?
- Decomposer community: bacterial, fungal species.
- Physiochemical environment: temperature and water.
What are the three mechanisms of decomposition?
- Catalysis: enzymatic reactions breaking complex compound down into simple ones.
2,. Communication: physical and mechanical breakdown of matter. - Leaching: soluble material removed by water.
What is the post mortem interval?
- Estimated time after death has occurred.
- Evidence can be collected from the body and environment to come to an estimation.
What are the two methods used for estimating the PMI?
- Rate method- measuring the change of a process which takes place at a known rate.
2. Occurrence methods: comparing the occurrence of events which took place at a known times with the occurrence of the death.
What are the traits shown in the fresh stage of decomposition?
-Pallor mortis occurs straight after death.
- Skeletal muscles relax.
- Blood becomes acidic gradually.
- Body temperature changes and autolysis occurs.
What is pallor mortis and how is it caused?
-When the skin goes paler in colour.
- Occurs straight after death and this is because the blood has stopped circulating the body.
What is autolysis?
- It is when cells break down by their own enzymes.
- When an individual dies, the cells are deprived of oxygen and it is required for them to survive.
- Cells no longer have a membrane and they swell and eventually burst.
What is algor mortis?
- The cooling of the body after death.
- Most popular area to estimate the PMI.
- After death the body will cool in temperature until it reaches an ambient temperature; no longer useful afterwards.
Which law helps us algor mortis?
- Newtons law of cooling
Name five different factors that influence algor mortis?
- Body size.
- Diseases/drugs
- Immersion of water
- Cause of death
-Clothing - Dismemberment
What are some challenges with algor mortis?
- It can be invasive when trying to establish the temperature from the liver.
- The positioning of the body.
- Seasonal temperature changes.
What is the diagram called that can be used to help estimate algor mortis and its drawbacks?
- The diagram is called Henssge nomogram.
- A subjective methods as there should be no strong radiation and high thermal conductivity of the surface underneath the body.
-Also the diagram can only be used if the body is in its original location when the time of death occurred.
What are other names that livor mortis can be called?
- Lividity and hypostasis.
What is livor mortis?
- It is a characteristic that can be identified after death due to the pink/ purplish discolouration of the skin.
- Discolouration of the skin occurs as blood circulation has stopped and it is not flowing through the body, so gravity makes the blood settle in certain places of the body.
- If certain parts of the body are in contact with a surface, compression of the blood vessels occur and result in displacement of blood.
- Occurs internally and externally in the body.
What three factors influence livor mortis?
- Ambient temperature.
- Cause of death.
- Diseases/ drugs.
- Clothing.
What are some challenges with livor mortis?
- If an individual has darker skin tones.
- Body is deposited/ found in water.
- Movement of body after death; can see distinctive bands.
- Misinterpretation of lividity and instead it could be CO/ cyanide poisoning.
What is blanching?
- It is when pressure is applied to the skin and the blood is displaced by the pressure and it results the skin in a paler colour compared t the rest of the body.
When does livor mortis become fixed?
- 3-6 hours after death, blood vessels break down and blood disperses into the surrounding tissue.
- Becomes fixed after 8-12 hours.
What does aetiologies mean?
- The cause, set of causes, or manner of causation of a disease or condition.
What does putrefaction mean?
The process of decay and rotting in a body or organic matter.
What is rigor mortis?
- It is the stiffening of muscle after death.
- Stiffening of muscles occurs due to the depletion of ATP and the build up of lactic acid and calcium.
- Is a slow progression and usually takes place 2 hours after death.
What is Nysten’s rule?
- When a body is in a supine position, rigorously mortis starts from the lower jaw, then moving down to the neck and then working its way down to the lower parts of the body.
What Is cadaveric spasm?
- Muscle stiffening sets in immediately.
What are ocular changes?
- Clouding of the cornea; occurs 20-3 hours after death.
- Occurs in dry, arid conditions.
What is Tache Noir?
-The ‘drying out; of the corneal surface.
What can the gastric content s of an individual tell us?
- Can tell an individuals last meal such as the colour, volume and residual wood and pills.
- PMI can be estimated on how empty a stomach it.
