Irrversible Cell Injury Flashcards
What is irreversible cell injury ?
Severe cell injury that the cell can NOT recover after the removal of adverse influence .
Necrosis
It is changes that accompany the cell death , generated by degradative action of enzymes released out of lysosomes of the dying cell itself OR the leukocytes (WBCs)
The major characteristic of necrosis is :
The cell’ s inability to maintain plasma membrane integrity THEN leakage of intracellular proteins
Necrosis detection in MI & hepatitis :
- Necrotic myocytes release certain isoform of creatine kinase and contractile protein troponin within the circulation
- Necrotic hepatocytes release alkaline phosphatase and transaminases (GPT and GOT )
Necrosis appearance ultrastructurally :
- Fragmentation of plasma and organelles membrane
- Myelin figures
- Lysosomes rupture
- Nuclear condensation or dissolution
- ER swelling with the loss of ribosomes
6.mitochondrial dilatation
Necrosis appearance in LM :
- Increased cytoplasmic eosinophilia ( eosin binds with denatured cytoplasmic proteins )
- Glassy homogenous appearance ( loss of glycogen particles )
- Vacuolated cytoplasm ( degradation of organelles )
- Myelin figures ( replacement of dead cells usually )
Necrosis patterns :
- Coagulative necrosis
- Liquefactive necrosis
- Caseous necrosis
- Fat necrosis
- Fibrinoid necrosis
- Gangrene necrosis
Coagulative necrosis is characterised by :
Preservation of tissue architecture
Coagulative necrotic cells appear eosinophilic and anucleated ( karyolysis )
General mechanism of coagulative necrosis :
- Proteins denaturation and Inhibition of enzyme activity
- leading to blocking of proteolysis of dead cells
Coagulative necrosis occur only in :
Solid organs except brain
Coagulative necrosis Example :
MI
How to determine necrotic myocardial cells :
Acidophilic , loss of nuclei and striations
How to get red of coagulatied necrotic cells :
Fragmentation and phagocytosis
Liquefaction necrosis is characterised by :
Softening of of the necrotic tissue
Liquefaction necrosis is found in :
- Brain infarction
- Abscess
Liquefaction necrosis in brain is due to :
Hydrolytic action of enzymes
The organelles involved in Liquefactive necrosis in abcsess :
Lysosomes of the inflammatory cells invading the necrotic tissue
Abscess occurs due to
Pyogenic bacterial or fungal infection producing pus
Pus definition
Necrotic tissue with inflammatory cells are transformed into thick yellow creamy material
Liquefactive necrosis mechanism
- Complete digestion of dead cells
- Transformation into a viscous liquid
- Loss of the general architecture of tissue
How to get rid of Liquefactive necrotic tissue
Phagocytosis
Caseous necrosis gross appearance :
- cheesy yellow white necrotic area
- Nicrotic material : soft greasy
Caseous necrosis macroscopically
- complete loss of tissue architecture and fragments ( structureless and amorphous granulomas )
Caseous necrosis microscopically :
- Epithelioid cells ( altered macrophages )
- Granuloma ( whole necrotic lesion )
- Langerhan’s giant cells ( multi uncleared giant cells )
Caseous necrosis found in diseases as :
- Tuberculous infection
- Tuberculous lymphadenitis
Severe tuberculosis is characterised by :
There are cystic spaces ( cavitation ) in the destructed tissue
What is fat necrosis ?
Fat destruction due to release of activated pancreatic lipases
Where could fat necrosis be found ?
Fat cells in and around the pancreas , in omentum , and subcutaneous tissue .
Cases related to fat necrosis :
- Acute hepatitis
2.trauma to fat
What happens in acute pancreatitis ?
- Pancreatic enzymes are released out of the acinar cells and ducts that liquefy the membrane of fat cells
- Lipases split of the triglycerides within the cytoplasm of fat cells
- Accumulated fatty acids combine with calcium
Trauma to fat
In breast and subcutaneous tissue
How to detect fat necrosis
Staining of oil red O or Sudan IV
H&E stain
Fat appearance in Oil red O Or Sudan IV :
Red intercytoplasmic granules
H&E stain
What is Fibrinoid Necrosis in polyarthritis nodosa :
Antigen- antibody complex combine with fibrin ( that has leaked out of vessels ) then deposit in the wall of arteries involved in immune reaction
Fibrinoid necrosis is a special for :
Small blood vessels
Appearance of Fibrinoid necrosis in polyarthritis :
Bright pink and homogenously red amorphous appearance
Fibrinoid appearance is involved in :
- Blood vessels in malignant hypertension
- Blood vessels involved in immune reaction
Gangrenous Necrosis :
Infarction + superimposed infection of saprophytic bacterial
Types of gangrene
- Wet gangrene
2.dry gangrene
3.gas gangrene
Wet gangrene
Intestine
Wet gangrene
DM
Gas gangrene
Clostridial welchii infection
Gross appearance of gangrenous digit :
The nail is bluish-black
The skin is purplish red
- cased by thrombosis
