Cell Injury, Adaptation & Cell Death

Question 1

What characterizes necrosis?

Answer 1

• intense eosinophilia (pinkness) of cytoplasm
• pyknosis (shrinkage)
• karyorrhexis (pyknotic nucleus fragments)
• karyolysis (dissolution of nucleus)

Question 2

Coagulative Necrosis?

Answer 2

• most common
• cells are like ‘ghosts’ of themselves
• typical of ischemia (i.e. in myocardial cells)

Question 3

Liquefactive Necrosis?

Answer 3

• rapid loss of tissue architecture and digestion of dead cells
• most often in CNS
• typical of bacterial damage

Question 4

Fat Necrosis?

Answer 4

• released enzymes digest fat that complexes with calcium
• this forms chalky-white deposits
• specific to adipose tissue
• i.e. pancreatitis, breast tissue damage

Question 5

Caseous Necrosis?

Answer 5

• soft, friable, ‘cheesy’ material

- characteristic of TB

Question 6

Gangrenous Necrosis?

Answer 6

• “wet gangrene” = coagulative necrosis when there’s a superimposed infection with a liquefactive component
• “dry gangrene” = if necrotic tissue dries out (no infectious component), becomes dark and mummified

Question 7

Define Necrosis

Answer 7

uncontrolled process of cell death in response to overwhelming injury

Question 8

Define Apoptosis

Answer 8

• energy-dependent process specifically designed to switch off unneeded/damaged cells and eliminate them
• physiologic or pathologic (following radiation injury)

Question 9

Describe the process of apoptosis

Answer 9

• gene activation
• activation of caspases (proteases) –> breaks down cytoskeleton
• activation of endogenous endonucleases —> ATP dependent fragmenting of DNA, cleaved into regular nucleosomal fragments (laddering)
• nucleus collapses
• cell shrinks and is cleaved into apoptotic bodies
• apoptotic bodies and engulfed by phagocytic cells