Lecture 2 Flashcards

1
Q

What does the onset and rate of PM changes depend on

A
  1. Environmental and body temperature 2. Cause of death
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2
Q

Are PM changes pathological

A

No, because it occurs after death

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3
Q

What must you refrigerate bodies and not freeze them

A

Intra and extracellular crystals disrupt cells and makes histopathological interpretation difficult

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4
Q

What tissues decompose more rapidly

A

GIT and nervous tissue

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5
Q

What do tissues need to be fixed in to be able to determine subtle histological changes

A

Formalin

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6
Q

Define Rigor Mortis

A

Contraction of muscles after death

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7
Q

Why does rigor mortis occur

A

Depletion of glycogen prevents synthesis of ATP after death and without ATP the muscle fibres do not relax, resulting in contraction of muscles and immobilisation of joints

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8
Q

What muscles have rigor mortis first

A

Involuntary muscles then voluntary muscles starting with the head and defending to the trunk and libs

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9
Q

When does rigor mortis occur

A

1-6 hours of death

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10
Q

How long can rigor mortis persist

A

1-2 days

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11
Q

What animals have stronger rigor mortis

A

Muscular animals

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12
Q

What accelerates onset of rigor

A

High temperature and activity before death

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13
Q

What animals may not show rigor mortis

A

Animals with cachexia or extreme malnutrition

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14
Q

What don’t animals with cachexia or extreme malnutrition show rigor

A

Because stores of ATP and glycogen are so low that contraction of myofibres is not possible

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15
Q

What is Algor Mortis

A

Gradual cooling of the cadaver

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16
Q

With algor what is cooling dependent on

A

Temperature

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17
Q

What not to confuse lens opacity with

A

Cataracts

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18
Q

What is another name for livor mortis

A

Hypostatic congestion

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19
Q

What is livor mortis/hypostatic congestion

A

Gravitational pull of blood to the down side of the animal

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20
Q

When does livor mortis/hypostatic congestion occur

A

Within an hour of death

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21
Q

where is livor mortis/hypostatic congestion seen

A

Externally in the skin

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22
Q

What colour animal is livor mortis/hypostatic congestion best seen in

A

On white animals

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23
Q

What do you get with bloating

A

Organ displacement

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24
Q

Where can you see livor mortis/hypostatic congestion internally the best

A

Lungs

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25
Q

What happens before the blood clots

A

Erythrocytes settle to the bottom of large vessels

26
Q

What does the settlement of erythrocytes mean

A

2 portions - Bottom red mass - Upper pale yellowish mass

27
Q

What is the bottom red mass known as

A

Red current jelly clot

28
Q

What is the upper pale yellowish mass known as

A

Chicken fat clot

29
Q

What is separation of blood clots dependent on

A

Erythrocyte sedimentation rate

30
Q

What animal is Erythrocyte sedimentation rate high in

A

Horses and animals with systemic inflammatory reaction

31
Q

Why is ESR high in animals with systemic inflammatory reaction

A

Increased plasma fibrinogen which causes erythrocytes to stack

32
Q

What does post mortem clotting need to be distinguished from

A

Antimortem thrombi and thromboembolism

33
Q

How do you remove the clot

A

Forceps

34
Q

Describe postmortem clots

A

Unattached to vessel walls, tend to be shiny and wet and form a perfect cast of vessel lumens

35
Q

Describe antimortem arterial thrombi

A

Attached, tend to be dry and duller and are laminated with tail extending downstream

36
Q

Describe antimortem venous thrombi

A

Loosely attached and may resemble postmortem blots

37
Q

Define autolysis

A

Breakdown/decomposition of cells after death

38
Q

Why does decomposition upon death occur

A
  1. Failure to maintain ion gradient and cell membrane integrity 2. Cell membrane degrades and ruptures 3. Cell contents spill into interstitial and their cytology proteolytic enzymes further degrade exposed cells 4. Chain reaction of decomposition that results from digestion of tissue by intrinsic enzymes is called autolysis
39
Q

What is another pathway for decomposition due to bacterial proliferation and consumption

A

Putrefaction (gas production and odours)

40
Q

Explain putrefaction

A

Bacterial metabolism and dissolution of tissues result in colour and texture change - softening of tissues is due to autolysis of cells and actions of bacteria - Tissue becomes friable

41
Q

After death the body decomposes. What is the first step and what occurs later on

A
  1. Autolysis 2. Bacterial putrefaction
42
Q

What is the difference between mummification and maceration

A

Mummification is desiccation with no bacteria where maceration has bacteria

43
Q

What does haemoglobin imbibition refer to

A

Pink/red staining of tissue

44
Q

What occurs in haemoglobin imbibition

A

Haemoglobin from lysed erythrocytes penetrates vessel walls and surrounding tissues

45
Q

Where is haemoglobin imbibition commonly seen

A

Heart and walls of large arteries and in veins several hours after death

46
Q

Where is haemoglobin imbibition very obvious

A

In aborted foetuses that have been retained for several hours or days in the uterus

47
Q

When does bile imbibition occur

A

Several hours after death

48
Q

What happens with bile imbibition

A

Bile from gall bladder penetrates its wall and stains adjacent tissue yellowish green

49
Q

Where is bile ambition seen

A
  1. Adjacent liver and intestines in contact with the gall bladder 2. Adjacent to large bile duct
50
Q

What are some other post mortem changes

A
  1. Bloating - ruminants, horses 2. Organ displacement by gas in the intestinal tract 3. Pale areas in the liver 4. Mucosal sloughing in the rumen rapidly occurs 5. Bloody nasal discharge 6. Rectal or vaginal prolapse are usually artefacts
51
Q

What is bloating difficult to distinguish from

A

Anti-mortem bloat (luminal tympany) in ruminants

52
Q

Why do pale areas in the liver occur post mortem

A

Due to increased intra-abdominal pressure from gas filled intestines or focal action of postmortem bacteria

53
Q

Why does Rectal or vaginal prolapse occur

A

due to gas distention of abdominal viscera

54
Q

Why is bloat common in ruminants

A

Rumen microbes may produce abundant gas, causing carcass to swell tremendously

55
Q

Explain

A

Lens opacity from cooling - algor mortis

56
Q
A

Hypostatic congestion - livor mortis

57
Q
A

Hypostatic congestion

58
Q
A

Postmortem clotting

59
Q
A

Postmortem autolysis

60
Q
A

Haemoglobin imbition

61
Q
A

Bile imbition

62
Q
A

Rectal prolapse