Cell degeneration and death 2

Question 1

Physical causes of cell injury

Answer 1

UV radiation

Excessive heat or cold

Question 2

Mechanisms by which cells are deprived of O2

Answer 2

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

Question 3

Describe the cellular events leading to necrosis in hypoxia/ischemia

Answer 3

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

Question 4

Factors influencing significance of ischemia

Answer 4

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

Question 5

Anoxic cellular injury

Answer 5

inadequate oxygenation of blood

• anemia
• pneumonia

Question 6

Arterial vs venous impairment of blood flow

Answer 6

arterial initially pale

venous deep red-balck congested

Question 7

Appearance of an infarct is dependent on

Answer 7

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

Question 8

Venous infarct commonly are associated with?

Answer 8

displacements or twists in the intestine

Question 9

Reperfusion injury

Answer 9

• 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

Question 10

Watershed

Answer 10

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

Question 11

Renal papillary necrosis

Answer 11

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

Question 12

Describe the process of frostbite

Answer 12

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

Question 13

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

Answer 13

ergotamine toxin–> vasoconstriction–>ischemia

Question 14

Patterns of necrosis

Answer 14

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)

Question 15

If necrosis is severe how does it heal?

Answer 15

heals by scarring

Question 16

The significance of necrosis is related to its:

Answer 16

location
size
rate of development
sequelae