Exam 4 Lecture Notes- Postmortem Chemical Change Flashcards Preview

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Flashcards in Exam 4 Lecture Notes- Postmortem Chemical Change Deck (68)
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1

  • 10 types of decomposition:
    • Autolysis
    • Fermentation
    • Saccharolysis
    • Proteolysis
    • Lipolysis
    • Hydrolysis
    • Bacterial Decay
    • Bacterial Putrefaction
    • Hemolysis
    • Oxidation
  • Rigor Mortis
  • Postmortem Caloricity
  • Change in pH
  • Postmortem Stain

Postmortem Chemical Changes

2

Separation of compounds into similar substances by the action of microbial and/or autolytic enzymes.

(general term)

Decomposition

3

Self destruction of cells; decomposition of all tissues by enzymes of their own formation without microbial assistance.

  1. Enzymes
  2. Co-enzymes
  3. Anti-enzymes
  4. Lysosomes

Autolysis

4

Chemical catalysts which are employed by the tissue cells for the digestion and metabolism of food substances during life.

Enzymes

5

Accelerator substances which increase the activity of enzymes. 

Co-enzymes

6

Substances similar to antibodies. They have a marked inhibitory action on certain enzymes and serve to protect the living tissues against their own digestive agents (autolysis).

Anti-enzymes

7

A membrane bound body within a cell containing a microscopic droplet of acid hydrolase. At death, acid hydrolase is released (kicks in autolysis). This enzyme is able to break down all matter, fats, carbohydrates and protein. They are capable of destroying the cell membranes, ultimately destroying tissue membrane- this occurs shortly after death.

Lysosomes

8

Organelles within cells that contain the digestive enzyme of a cell. The primary enzyme is acid hydrolase. After death, the pH of tissue changes from slightly alkaline to slightly acid causing the membranes around this organelle to rupture. Self-digestion begins with the release of enzymes.

Role of the Lysosome

9

  • Amino acids
  • Sugars
  • Fatty Acids
  • Glycerol

End Products of Autolysis

10

Bacterial decomposition of carbohydrates. It occurs simultaneously with putrefaction and constitutes a major embalming problem. It is the reduction of carbohydrates into simpler substances usually carbon dioxide and water.

  • Bacteria, yeasts, and autolytic enzymes play a key role in this after death.

Fermentation

11

  • Anoxidative bacterial fermentation anaerobic type.
  • Oxidative bacterial fermentation aerobic type.

Types of Fermentation

12

No oxygen involved.

Aboxidative bacterial fermentation anaerobic type

13

Oxygen is directly involved.

  • This type will always dominate the fermentation process.

Oxidative bacterial fermentation aerobic type

14

The decomposition of sugars; similar to fermentation, bacteria, yeasts and autolytic enzymes play a key role in the process.

Saccharolysis

15

The decomposition of proteins.

  1. Putrefaction
  2. Decay

Proteolysis

16

The decomposition of proteins by action of enzymes of anaerobic bacteria. It is the most unequivocal sign of death.

  • Distinct, foul odor more likely to occur with this.

Putrefaction

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The decomposition of protein caused by the action of enzymes of aerobic bacteria.

  • Foul odors are much less likely

Decay

18

The decomposition of lipids (fats). Will occur concurrently with the other types of decomposition.

Lipolysis

19

The decomposition of tissue caused by molecules of water, simply, splitting by water.

Hydrolysis

20

The destructive influence encountered from tissue acidity which beings to form shortly after death, reaching it's peak during rigor mortis.

One of the earliest postmortem chemical changes

21

  • The source of the acid is carbon dioxide accumulated in the tissues as a result of:
    • Cell metabolism
    • The absence of blood circulation to carry the waste material away from the tissue.
  • Carbon dioxide + water --> Carbonic Acid

The destructive influence encountered from tissue acidity (beginning shortly after death)

22

As bodily tissue reaches this pH (in which bacteria will thrive), carbonic acid will directly react with protein causing it to breakdown into amino acids.

  • Hydrolysis of protein will begin putrefaction

pH of 8

23

  • Color
  • Odor
  • Purge
  • Desquamation (skin slip)
  • Accumulation of gas in viscera, cavities, and other body tissues.

Cardinal Signs of Decomposition (list question)

24

  1. Yellow green to green
  2. Pink-red-purple-brown
  3. Dark Brown

Color

25

First external sign of decomposition appears as a silver dollar size circle over the right inguinal or iliac region (lower right quadrant of the abdomen).

  • The activity of E.coli causing visceral gas with a combination of hydrogen sulfide and hemoglobin results in a spreading green discoloration eventually covering the body.

Yellow Green to Green

26

Due to hemolysis resulting in extravascular postmortem stain.

Pink-Red-Purple-Brown

27

Leatherized condition due to postmortem dehydration.

  • Example: Freezer Burn

Dark Brown

28

Putrefaction is characterized by a nauseating odor resulting from simple amines, complex amines, and the end products of putrefaction.

  • Much less noticeable in decay

Odor

29

  1. Hydrogen Sulfide
  2. Hydrogen Phosphide
  3. Ammonia
  4. Mercaptans

Examples of odor causing gas

30

This is completely neutralized by ammonia.

Formaldehyde

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