3. Decomposition Flashcards
Define decomposition
A process which begins with death and tends to appear after the other post mortem changes have occurred (rigor mortis etc)
The loss of soft tissue resulting in skeletonisation - divided into autolysis and putrefaction
When does autolysis occur?
When hydrolytic enzymes (lysosomes) are released into the cytoplasm where they start to digest carbohydrates and proteins
What causes autolysis?
Lack of oxygen
What happens during autolysis?
Carbon monoxide and waste products build up and increase cell acidity
Cell enzymes attack cell walls
Release of nutrient rich fluid into surroundings initiates putrefaction
What is autolysis dependent on?
Temperature
What allows putrefaction to occur?
Autolysis creating an anaerobic environment
What happens during putrefaction?
Anaerobic bacterial activity cause soft tissues to break down into gases, liquids and salts
Aerobic bacterial activity occurs alongside anaerobic bacterial activity
Produces large amounts of gases and aromatic organic compounds which results in bloating of the body
What fuels putrefaction?
The release of carbohydrates from autolysis
What are the signs of putrefaction?
Discolouration
Degradation - loss of anatomic integrity of skin and other tissues
Distension - bloating
Dissolution - liquefaction
What is the order of putrefaction?
Intestines, stomach, digestive organs, heart, blood Air passages and lungs Kidneys and bladder Brain and nervous tissue Skeletal muscles Connective tissue and integument Bones
Principle stages of decomposition
Fresh Initial decay (bloating) Putrefaction (bloating) Black putrefaction (active decay) Butyric fermentation (advanced decay) Dry decay Skeletonisation
What happens at the fresh stage?
Autolysis within cells
What happens at the initial decay stage?
Initial changes can only be seen microscopically but gradually become more obvious as:
Marbling
Skin slippage
Blistering
What happens at black putrefaction (Active decay) stage?
Bloated body eventually collapses leaving a flattened body whose flesh has a creamy consistency
Exposed parts of body are black
Very strong smell
What happens at butyric fermentation (advanced decay) stage?
All remaining flesh is removed over this period and body dries out
Cheesey smell caused by butyric acid
Surface in contact with ground covered in mould as body ferments
What happens at dry decay stage?
Body is dry
Remnants of soft tissue disappear leaving bones
Skin slippage
Release of hydrolytic enzymes at dermal epidermal junction results in loosening of the epidermis
Collections of fluid under skin = bulla
What creates marbled skin?
Autolysis of red blood cells (hemolysis)
Hydrogen sulfide also reacts with hemoglobin to form sulfehmoglobin (green pigment)
What is bone diagenesis?
After skeletanisation bacteria continue to eliminate the collagen
After this, bone breakdown is to do with chemical equilibria between soil/water and bone
What conditions does mummification require?
Dry conditions which mean no putrefaction occurs
Lack of moisture is essential for this but can occur in cold or hot
What conditions does the formation of adipocere require?
Damp environments
also known as saponification
What is embalming?
Human intervention to prevent the decompositional process
