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Pathology > Exam 2: Gangrene, Postmortem Change, and Forensics > Flashcards

Exam 2: Gangrene, Postmortem Change, and Forensics Flashcards

1
Q

What is dry gangrene?

A

A classic manifestation of coagulative necrosis
Infarction of external tissues, leading to coagulative necrosis and mummification
Arterial occlusion

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2
Q

Where does dry gangrene often occur?

A 
Leg
Ear
Tail
Udder
Umbilical stump
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3
Q

What is an example of dry gangrene?

A

Frostbite

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4
Q

What is frostbite?

A

Extreme cold- direct freezing, ice crystals disrupt cells/vessels leading to infarction

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5
Q

What happens to tissues with dry gangrene?

A

They darken due to iron sulfide accumulation

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6
Q

What is the result of dry gangrene?

A

Autoamputation

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7
Q

What is wet gangrene?

A

Areas of coagulative necrosis that are further infested by saprophytic or putrefactive bacteria

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8
Q

What happens to the tissue with wet gangrene?

A

Soft, moist, red/black, gas bubbles from saprophytes

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9
Q

What can you get wet gangrene from?

A

Extremites (tight bandages, arterial damage, trauma)

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10
Q

What happens in animals that survive wet gangrene?

A

Inflammation separates dead tissue leading to sloughing

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11
Q

What is gas gangrene?

A

Wet gangrene with anaerobic fermentation and gas production

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12
Q

What is gas gangrene often called?

A

Malignant edema

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13
Q

How does gas gangrene cause necrosis?

A 
Wounds have leakage of IV compounds, which introduce Clostridium septicum and others
Proliferate and produce toxins
Damage vessels
Hemorrhage and edema
Necrosis
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14
Q

What is an example of gas gangrene?

A

Black leg

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15
Q

Describe what happens with blackleg

A

C. chauveoi spores latent in muscle
Bruising injury causes hemorrhage
Anaerobic environemnt
Bacteria proliferate, produce toxins

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16
Q

Describe postmortem change pathology

A

Immediately after death, a sequence of physical and chemical changes
Unavoidable, irreversible, progressive
Occur with constancy, but subject to great variability

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17
Q

What are the 3 basic processes of postmortem change?

A

Autolysis
Putrefaction
Diagenesis

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18
Q

What is the time between the last heart beat and decomposition?

A

4 minutes

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19
Q

Describe what occurs between the last heart beat and the start of decompostion

A 
Oxygen deprivation
CO2 increase, pH drops
Wastes accumulate
Chemical disorganization
Metabolic breakdown
Cell death
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20
Q

What is autolysis?

A

Self digestion due to endogenous enzymes

Natural breakdown of cells by their own lipases, proteases, and carbohydrates

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21
Q

What can autolysis occur in?

A

Living tissues (with large infarcts) or postmortem

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22
Q

Why is postmortem autolysis different from necrosis?

A

Circulation

23
Q

What are the 2 fates of proteins?

A

Lysis (liquefactive necrosis) or denaturation (coagulative necrosis)

24
Q

In what tissues does autolysis progress most rapidly?

A

Those with high enzyme content

25
Q

List the tissues in order of speed of autolysis from fastest to slowest

A 
Retina
Brain
Testis
Stomach/intestine
Pancreas/liver
Lung/airways
Kidney
Muscle/heart
Connective tissue and integument
26
Q

What allows putrefaction to occur during autolysis?

A

Lack of innate response and sufficient nutrient rich fluid

27
Q

What is putrefaction?

A

The portion of decomposition where the action of micro-organisms cause the dissolution of tissues into gases, liquids, and simple molecules

28
Q

Where do the organisms involved in putrefaction derive from?

A

Internal and external environments

29
Q

What are external and internal factors involved in putrefaction?

A 
Species
Content in GI tract
Body temp
Environment temp/humidity
Location/position
Storage of body
30
Q

What are constraints of decomposition?

A

Temperature
Water/moisture
Acidity and alkalinity

31
Q

What is thee most important variable in determining the overall velocity of decay?

A

Temperature

32
Q

How does water/mositure constrain decomposition?

A

Stabilizes temp
Buffers tissue/environmental pH
A hydrogen source for biochemical reaction in dying tissues, microbes, saprophytes
Dilutes (a solvent for polar molecues)

33
Q

What are the 4 basic stages of decpmposition?

A

Fresh
Bloat/putrefaction
Active decomposition
Advanced decay/butyric fermentation/skeletonization

34
Q

Describe the fresh stage of decomposition

A

Begins minutes after death, lasting several hours
Predominance of autolysis
Rigor mortis, livor mortis, algor mortis
No smell of decay

35
Q

Describe the bloat/putrefaction stage of decomposition

A

Gases in tisuses, green discoloration
Marbling
Smell of decay, tissues are friable

36
Q

Describe active decomposition

A

Skin sloughs, soft tissues are liquefied, rupture of body cavities Extensive maggot activity/carnivore activity
Muscles achieve putty-like consistency

37
Q

Describe advanced decay/butyric fermentation/skeletonization

A

Rupture of cavities, loss of internal tissues, flattening of the carcass
Loss of fluids, smell abates
Butyric acid produced

38
Q

What is rigor mortis?

A

Stiffening of muscle

39
Q

Describe what happens during rigor mortis

A 
Observed first in small muscles
Cold prolongs
Resolution occurs due to muscle decomposition
Affects irises
Affects heart
40
Q

What is livor mortis?

A

Dependent surface purpling due to intravascular blood pooling

41
Q

Describe what happesn during livor mortis

A

Loss of blood pressure and loss of tissue pressure, leaves only underlying surface pressure
Occurs in all fluid compartments
Colors change
Initially non-fixed

42
Q

What is algor mortis?

A

Cooling of a body to environmental equilibrium

43
Q

What is hemoglobin imbibition?

A

Staining of tissue by free hemoglobin

44
Q

What is bile imbibition?

A

Yellow/green discoloration of the extrahepatic biliary system and nearby tissues

45
Q

What is hydrogen sulfide?

A

Produced by putrefaction, rapidly diffuse through tissues

46
Q

Describe postmortem clotting (cruor)

A

Immediately after death, blood is coagulable

47
Q

What is marbling?

A

Spread of hemoglobin from blood vessels with admixture of hydrogen sulfide leading to iron sulfide in vessels
Forms a marbled appearance in the skin and certain tissues

48
Q

What is mummification/

A

Modified putrefaction due to dehydration

49
Q

What are ocular changes?

A

Clouding of the cornea when chilled

50
Q

What is putrefaction?

A

anaerobic environments

Digest fats, CHOs, proteins to produce acids, gases, and molecules

51
Q

What is adipocere-gravewax?

A

Alteration of the carcass soft tissues to grey/white soft substance that hardens and resists decomposition

52
Q

What role do insects have in decomposition?

A

They are important in speed and completeness of decomposition

53
Q

What are scavengers?

A

Often dogs, wild animals, livestock, rodents
Early removal of eyes, perioral and perianal soft tissues
Disarticulation, consumption of soft tissues, gnawing of bones

54
Q

What is pink teeth?

A

Hemoglobin infiltrates denting tubules

Pathology (16 decks)

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