Pathoma: Cell Death

Question 1

What is the morphologic hallmark of cell death?

Answer 1

Loss of nucleus

Question 2

3 ways cell death occurs

Answer 2

pyknosis, karyorrhexis, karyolysis

Question 3

Pyknosis

Answer 3

shrinking of nucleus

Question 4

Karyorrhexis

Answer 4

breaking up of nucleus

Question 5

Karyolysis

Answer 5

nucleus broken down into building blocks

Question 6

2 mechanisms of cell death

Answer 6

necrosis

apoptosis

Question 7

Necrosis

Answer 7

death of a large group of cells followed by acute inflammation

Question 8

Is necrosis pathologic or physiologic?

Answer 8

pathologic only

Question 9

Coagulative necrosis

Answer 9

necrotic tissue that remains firm
cell shape and organ structure are preserved by coagulation of cellular proteins
Nucleus disappears

Question 10

What is coagulative necrosis characteristic of?

Answer 10

ischemic infarction of any organ except brain

Question 11

What is the shape and color of the necrotic tissue?

Answer 11

wedge-shaped and pale

wedge points to the area of occlusion

Question 12

Red infarction

Answer 12

arises if blood re-enters a loosely organized tissue

testicle during testicular torsion due to the vein being blocked and blood filling testicle

Question 13

Liquefactive necrosis

Answer 13

necrotic tissue that becomes liquefied

enzymatic lysis of cells and proteins–>liquefaction

Question 14

What is liquefactive necrosis characteristic of?

Answer 14

brain infarction: because of microglial cells that contain hyrolytic enzymes
Abscess: neutrophils contain hyrolytic enzymes
pancreatitis: pancreatic enzymes activated

Question 15

Gangrenous necrosis

Answer 15

coagulative necrosis that resembles mummified tissue (dry gangrene)

Question 16

What is gangrenous necrosis characteristic of?

Answer 16

ischemia of the lower limb and GI tract

if superimposed infection occurs–>liquefactive necrosis ensues (wet gangrene)

Question 17

Caseous necrosis

Answer 17

soft, friable necrotic tissue with “cottage cheese-like” appearance
coagulative and liquefactive necrosis

Question 18

What is caseous necrosis characteristic of?

Answer 18

granulomatous inflammation due to TB or fungal infection

Question 19

Fat necrosis

Answer 19

necrotic adipose tissue with chalky-white appearance due to deposition of Ca2+

Question 20

Saponification

Answer 20

fat binding with Ca2+
FA released by trauma or lipase joins with Ca2+
example of dystophic calcification

Question 21

What is fat necrosis characteristic of?

Answer 21

trauma to fat (e.g. breast)–>looks like a mass

pancreatitis-mediated damage of peripancreatic fat

Question 22

Metastatic calcification

Answer 22

calcification that occurs in multiple tissues due to a high serum Ca2+ or phosphate; not cancerous

Question 23

Fibrinoid necrosis

Answer 23

necrotic damage to blood vessel wall

leaking of proteins into vessel wall–>bright pink staining

Question 24

What is fibrinoid necrosis characteristic of?

Answer 24

malignant hypertension or vasculitis

preeclampsia–>fibrinoid necrosis of placenta

Question 25

Apoptosis

Answer 25

energy-dependent geneticaly programmed cell death
involves single cells or small groups of cells
NOT FOLLOWED BY INFLAMMATION

Question 26

Physiologic examples of apoptosis

Answer 26

endometrial shedding during menstrual cycle
removal of cells during embryogenesis
CD8+ T cell-mediated killing of virally infected cells

Question 27

Morphology of apoptosis

Answer 27

dying cell shrinks (becomes eosinophilic)
nucleus condenses and fragments
apoptotic bodies fall from cell and are removed by macrophages

Question 28

What mediates apoptosis?

Answer 28

Caspases

Question 29

Caspases

Answer 29

activate proteases (break down cytoskeleton)
activate endonucleases (break down DNA)

Question 30

3 pathways that activate caspases

Answer 30

intrinsic mitochondrial pathway
extrinsic receptor-ligand pathway
cytotoxic CD8+ T cell pathway

Question 31

Intrinsic mitochondrial pathway

Answer 31

cell injury, DNA damage, or decreased hormonal stimulation inactivates Bcl2
cytochrome c leads from inner mitochondrial membrane–>cytoplasm

Question 32

Extrinsic receptor-ligand pathway

Answer 32

FAS ligand binds FAS death receptor (CD95) on target cell: negative selection during cell cycle of T cell in thymus
TNF binds TNF receptor on target cell

Question 33

Cytotoxic CD8+ T cell pathway

Answer 33

perforins create pores in membrane of target cell

granzyme enters pores and activates caspases