Pathology Quiz2-Necrosis

Front 1

define necrosis

Back 1

the morphologic changes that follow cell death within living tissue (necrobiosis)
=Antemortem autolysis + heterolysis

Front 2

where does necrosis occur?

Back 2

in lethally-injured cells

Front 3

from what does necrosis occur?

Back 3

from the progressive degradative action of proteolytic lysosomal enzymes

Front 4

where do proteolytic lysosomal enzymes needed for necrosis come from?

Back 4

-dead cells temselves (autolysis)
-leukocytes recruited during inflammation (heterolysis)

Front 5

The morphologic appearance of necrosis is due to....

Back 5

- denaturation of intracellular protein
- enzymatic digestion of the cell
- inflammation (not present in post mortem autolysis)

Front 6

what can cause irreversible cell injury?

Back 6

-inherited (genetic)
-aquired
-physical (thermal, trauma, radiant energy)
-toxic -infectious
-metabolic (endocrinologic, immunologic, degenerative)
-nutritional -neoplastic

Front 7

list two main pathways of cell death

Back 7

1. oncosis: cell death by swelling
2. apoptosis: cell death by shrinkage, programmed cell death

Front 8

List histologic features of oncosis

Back 8

Nuclear changes:pyknosis, karyorrhexis, karyolysis

Cytoplasmic changes: cell swelling, increased eosinophilia, pallor(蒼白), vacuolation

Front 9

What does pyknosis lead to?

Back 9

shrunken, irregular, dark nucleus

Front 10

What does karyorrhexis lead to?

Back 10

fragmentation of the nucleus (nuclear envelope ruptured, with release of dark nuclear fragments into cytoplasm)

Front 11

what does karolysis lead to?

Back 11

basohilia of nuclear chromatin fades (hydrolysis from DNAse activity)

Front 12

Why does cell swelling occur during oncosis? what does it indicate?

Back 12

due to accumulation of water, fat, glycogen
swelling reflects membrane damage of irreversible cell injugy

Front 13

why do eosinophilia increase during oncosis?

Back 13

due to increased binding of eosin to denatured intracytoplasmic proteins, and loss of normal basophilia of ribosomal RNA

Front 14

Why do cells show pallor appearance during oncosis?

Back 14

due to loss of intracellular proteins, glycogen stores and organelles

Front 15

What does glassy appearance of cell during oncosis reflect?

Back 15

relfects glycogen loss

Front 16

Why does vacuolation occur during oncosis?

Back 16

since organelles are digested by enzymes, calcification and cell replacement by whorled phospholipids masses called myelin figures which may be phagocytosed, or further degraded into fatty acids, which can form calcium soaps

Front 17

Describe sequences of oncosis (necrosis) of small area

Back 17

-resorption & phagocytosis of necrotic material
-regeneration of tissue from labile/stable cell populations
-replacement and repair by fibrous tissue (fibrosis)
-replacement by fat (fat infiltration)

Front 18

Describe sequences of oncosis (necrosis) of large area

Back 18

-limited resorption & inflammation
-fibrosis and scar formation
-encapsulation surrounded and contained within a fibrous capsule to form
-calcificaion

Front 19

what are gross features of necrosis?

Back 19

1.pallor
2.loss in strength (soft, friable)
3.A zone of inflammation may border the necrotic tissue
4patterns of necrosis within the tissues

Front 20

Why are there several types (patterns) of necrosis?

Back 20

due to the different causative agent & local conditions, particularly the fluid or blood flow present in the lesion

Front 21

List 7 types of necrosis

Back 21

1. coagulative necrosis
2. liquefactive necrosis
3. Caseous necrosis
4. Gangrenous necrosis
5. fat necrosis
6. fibrinoid necrosis
7. collagen necrosis

Front 22

What are gross features of coagulative necrosis?

Back 22

tissues appear pale, often with a cooked apprearance

Front 23

What are histological features of coagulative necrosis?

Back 23

-tissues architecture is retained
-cell outlines preserved, but cells are shrunken
-cytosol is homogenenous and hyper-eoshinophilic
-nuclei are pyknotic, karyorrhectic, karyolytic or absent

Front 24

Why does coagulation necrosis occur?

Back 24

common acute hanges of hypoxic death of cells in acute bacterial or viral infections, anoxia or acute toxicoses
(it is characteristic of hypoxic cell death in all tissues except brain)

Front 25

What is a gross feature of liquefactive necrosis?

Back 25

liquefied areas

Front 26

What is a histological feature of liquefactive necrosis?

Back 26

-eosinophilic proteinaceous debris
-normal tissu architecture is lost

Front 27

What are causes of liquefactive necrosis?

Back 27

focal infection by pyogenic(化膿性の)bacteria that promote intense accumulation of inflammatory cells such as neutrophils and enzymic digestion

Front 28

where is liquefactive necrosis usually found?

Back 28

in the brain and cord (also intestinal mucosa, and pancreas)
Liquefactive necrosis is characteristic of hypoxic cell death of the brain and cord

Front 29

What are gross features of caseous necrosis?

Back 29

friable(もろい), granular to amorphous, off-white to pale yellow material with the consistency of cottage cheese

Front 30

What are histological features of caseous necrosis?

Back 30

-fragmented, coagulated cells
-tissue architecture is gone
-amorphous to granular nuclear -cytoplasmic degris

Front 31

what is the cause of caseous necrosis?

Back 31

rapidly growing tumors,fungal infections, and in some chronic bacterial infections

Front 32

What does dry gangrene imply?

Back 32

ischaemic coagulative necrosis without any fluid and gas built up.

Front 33

What does wet gangrene imply?

Back 33

ischiaemic necrosis mofified by the liquefactive action of putrefactive bacteria and the leukocytes they attract

Front 34

Where can dry gangrene be found?

Back 34

in extremities such as ears and udder

Front 35

Where is fat necrosis be seen?

Back 35

only in fat tissues
-common in ruminants

Front 36

What are clinical signs of fat necrosis?

Back 36

painful skin lumps and obstruction of GI and urinary tracts

Front 37

What are gross features of fat necrosis?

Back 37

-fat contains white, yellow to pink foci of calcium soap deposition at site of lipid breakdown
-chronic lesions are firm(fibrosis), white (Ca soaps) and chalky

Front 38

what are histological features of fat necrosis?

Back 38

-necrotic fat is not removed during preparation of paraffin-imbedded sections
-necrotic fat cells themselves are eosinophilic, but become basophilic when free fatty acids combine with Ca ions to form soaps
-chronic inflammation
-formation of multinucleate giant cells, fibrosis, and deposition of cholesterol

Front 39

What are spindle-shaped clear clefts which are found in histological section of cell experiencing fat necrosis?

Back 39

deposition of cholesterol

Front 40

what makes fat necrosis calcified?

Back 40

calcium soap foarmaiton

Front 41

what are causes of fat necrosis?

Back 41

-trauma
-Vit E deficiency
-Chronic inflammation
-Pancreatic disease

Front 42

Where is fibrinoid necrosis seen?

Back 42

blood vessels, especially medium-sized arteries

Front 43

Fibrinoid necrosis is often associated with ....

Back 43

-thrombosis of the vessel lumen
-oedema
-haemorrhage into adjacent tissue due to vascular leakage

Front 44

What are histologic features of fibrinoid necrosis?

Back 44

stains positively with fibrin stains such as PTAH & lendrums stain

Front 45

What are possible causes of fibrinoid necrosis?

Back 45

-sever vascular injury
-coagulation necrosis of the blood vessel wall mixed with blood clotting proteins which leak through a damaged intima
-seen in immune-mediated vasculitis, endotoxic shock, septicaemia, infection by endotheliotropic viruses

Front 46

What are histological features of collagen necrosis?

Back 46

-appears as condensed, fragmented, brightly eosinophilic denatured collagen
-damaged collagen is phagocytosed

Front 47

What are possible causes of collagen necrosis?

Back 47

-hypersensitivity reaction
-insect, spider bites
-mast cell tumours

Front 48

What is apoptosis responsible for?

Back 48

for both physiologic (eg. regression of the thymus, involusion of mammary gland, and regression of luteal cells)and pathologic events (eg.injuries)

Front 49

What is oncosis (necrosis) responsible for?

Back 49

only for pathologic events

Front 50

What are histologic features of apoptosis?

Back 50

-cell shrinkage
-chromatin condensation
-formation of cytoplasmic blebs (水泡)and apoptotic bodies
-rapid phagocytosis of apoptotic cells or apoptotic bodies by adfacent cells (usually macrophages)

Front 51

The histological features of apoptosis are conspicuous. Why?

Back 51

Because they usually involve only individual cells or small groups of cells, occur rapidly, and do not dlicit an inflammatory reaction

Front 52

what are gross features of apoptosis?

Back 52

none.
only microscopic changes are seen in apoptosis

Front 53

List biochemical features of apoptosis

Back 53

-protein cleavage
-DNA breakdown
-Phagocytic recognition

Front 54

How apoptotic cells prompt recognition and phagocytosis without release of pro-inflammatory cell components?

Back 54

since apoptotic cells undergo membrane translocation - the phospholipid, phosphatidlserine, flips out from the inner layers of the plasma membrane to be expressed on the outer layer of the cell

Front 55

List possible pathways for caspases activations

Back 55

-Extrinsic (death receptor-initiated)pathway
-Intrinsic (mitochondorial) pathway
-Cytotoxic T lymphocytes
-Establishment of apoptotic threshold

Front 56

How does extrinsic pathway activate caspases?

Back 56

by signalling to cells via 'death receptors' (members of the tumor necrosis factor receptor) on the cell surface.

Front 57

How does intrinsic pathway activate caspases?

Back 57

by signalling to cells via withdrawal of growth factors or hormones, and diverse forms of injury

Front 58

List stages of apoptosis

Back 58

1.Initiation phase: commitment to cell death by activation of caspases
2.Execution(執行)phase: executioner caspases activate laent cytoplasmic endonucleases and proteases
3.Removal of dead cells: apoptotic bodies bud off and phagocytosis