Causes Of Cell Injury

Question 1

What are the cytomorphologic changes of irreversible injury

Answer 1

Plasma membrane damage
Calcium entry into the cell
Mitochondrial swelling and vacuolization
Amorphous densities (calcium) inside mitochondria
Lysosomal swelling

Question 2

What are the general causes of injury

Answer 2

ATP depletion (hypoxia)
Membrane damage (e.g., oxygen derived free radicals)
Disturbances of cellular metabolism
Genetic damage

Question 3

What is acute cell swelling or hydropic degeneration

Answer 3

Increased cell size and volume from a water overload.
Due to loss of cell’s homeostasis secondary to mechanical, hypoxia, toxic, free radical, viral, bacterial and immune mediated injuries.
Specific gravity of Affected tissues

Question 4

What is ischemia

Answer 4

Reduced blood flow to a region to the body usually because of obstruction of the blood supply.

Question 5

What is the initial regulator of anaerobic glycolysis in acute hypoxia injury

Answer 5

Phosphofructosamine
Stimulated by drop of ATP
Result in production of intracellular lactate and inorganic phosphates

Question 6

How do cardiac glycosides of plant origin initiate acute cell swelling

Answer 6

Inhibit the action of Na-K ATP pump

Digitalis and ouabain

Question 7

What are the events in acute swelling caused by hypoxia or ischemia

Answer 7

Hypoxia
Decreased oxidative phosphorylation and ATP
Increase glycolysis, increased intracellular lactate, and depletion of glycogen store
Failure of Na-K ATP pumps due to ATP deficiency
Net influx of Ca, Na, and water with loss of intracellular Mg and K
Swelling of mitochondria, RER, Golgi, and outer nuclear membrane
Detachment of ribosomes, loss of micro villi, vesiculation of RER, formation of membrane whorls (myelin figures)
Severe disruption of cell membrane, Ca influx, cell enlargement and clearing of the cytosol
Irreversible cell injury, cell death=necrosis

Question 8

Which cells are susceptible to hydropic degeneration

Answer 8

Endothelium
Epithelium
Alveolar pneumocytes
Hepatocytes
Renal tubular epithelial cells
Neurons 
Glial cells of brain

Question 9

What is the ultra structure appearance of cell swelling

Answer 9

Distorted cilia, micro villi, and attachment sites
Blebbing of the cytoplasm
Cytoplasm is rarefied
RER, Golgi and mitochondria are dilated
Cytocavitary network fragmented
Proteins and calcium precipitate

Question 10

Endogenous pigments: What is lipofuscin ?

Answer 10

End result of autophagocytosis of cell consistuents that accumulates in lysosomes.
It can be seen in post mitotic cells (neurones and cardiac myocytes) or slowly dividing cells (hepatocytes and glial cells).
+ for PAS, Sudan black, acid-fast, and oil-red-O

Question 11

Endogenous pigments: What is ceroid ?

Answer 11

Similar process to lipofuscin but pathologic:
- vitamin E deficiency
- cachexia
- irradiation
- inherited disease neuronal ceroid-lipofuscinosis
+ for PAS, Sudan black, acid-fast, and oil-red-0.
Differentiation between lipofuscin and ceroid= lectin-binding histochemistry in humans and rats