Cell degeneration and death 2 Flashcards

1
Q

Physical causes of cell injury

A

UV radiation

Excessive heat or cold

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2
Q

Mechanisms by which cells are deprived of O2

A

inadequate oxygenation of the blood- ie hypoxia
inadequate o2 carrying capacity of blood- anemia
inadequate delivery of blood to tissue- ischemia
-vascular occlusion
-vasospasm
-shock
-infarct

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3
Q

Describe the cellular events leading to necrosis in hypoxia/ischemia

A

blood flow stops
lack of O2 and glucose
Mitochondrial ATP down
Depletion of cellular ATP
1.failure of protein synthesis (as it requires ATP)
2. failure of membrane Na/K pump- swelling of ER
3. anaerobic metabolism- low pH- activation of enzymes at low pH-necrosis
4. free Ca in cytoplasm -necrosis cascade
5. mitochondrial swelling

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4
Q

Factors influencing significance of ischemia

A

pre-existing collateral circulation
rapidity of development of ischemia
type of tissue/degree of metabolic activity
whether ischemia is due to defect in atrial or venous perfusion
whether or not there is reperfusion injury

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5
Q

Anoxic cellular injury

A

inadequate oxygenation of blood

  • anemia
  • pneumonia
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6
Q

Arterial vs venous impairment of blood flow

A

arterial initially pale

venous deep red-balck congested

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7
Q

Appearance of an infarct is dependent on

A

vanous vs atrial infarct
tissue- dense or loose
age of infarct
presence or absence of reperfusion

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8
Q

Venous infarct commonly are associated with?

A

displacements or twists in the intestine

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9
Q

Reperfusion injury

A
  • may damage ischemic tissue even more
  • reflow of blood into an area of moderate hypoxic insult results in additional damage to sublethally injured cells and may tip cells over the edge to necrosis
  • reflow increases free radical generation and inflammation
  • must be kept in persepctive in veterinary medicine
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10
Q

Watershed

A

between arterial fields in the equine large bowel where collateral circulation is poorest

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11
Q

Renal papillary necrosis

A

due to reduced perfusion of the medulla/papilla associated with NSAIDS administration in horses

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12
Q

Describe the process of frostbite

A

cold–>vasoconstriction–>ischeia coupled with direct freezing injury to cells

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13
Q

Explain how Ergotism (mycotoxin-related disease) can produce a similar lesion to frostbite

A

ergotamine toxin–> vasoconstriction–>ischemia

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14
Q

Patterns of necrosis

A

Distribution of noxious insult
-blood-borne or inhaled
Relative susceptibility of the cells or tissue
-cell metabolism (zone 3 hepatocytes vs zone 1)
-blood supply (end-artery OR collateral circulation)

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15
Q

If necrosis is severe how does it heal?

A

heals by scarring

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16
Q

The significance of necrosis is related to its:

A

location
size
rate of development
sequelae