Cell injury and death II Flashcards
What is coagulative necrosis? How does it appear histologically?
the outline of the dead cells are maintained and the tissue is somewhat firm. Nucleus disappears, and there is a wedge shaped and pale area where clot was
What is liquefactive necrosis?
the dead cells undergo disintegration and affected tissue is liquified via enzymatic lysis
What is caseous necrosis?
Accumulation of mononuclear cells that mediate the chronic inflammatory reaction and granuloma formation to an offending organism. The lipid in the wall of the organism can’t be fully broken down. The dead cells persist indefinitely as amorphous, coarsely granular eosinophilic debris
What is fat necrosis?
enzymatic digestion of fat via lipases. The FAs that are released react with Ca to form a soap-like substance
What is gangrenous necrosis?
Not a specific pattern of cell death, but usually describes limb loss due to lack of circulation
What type of cell injury results in coagulative necrosis?
Ischemia
What causes the maintenance of the outline of coagulative cells?
The CT framework
Why doesn’t the brain undergo coagulative necrosis? What type of necrosis does it undergo?
There is no CT framework, thus undergoes liquefaction necrosis
What type of necrosis occurs in abscesses? Why?
Liquefactive, b/c center made up of PMNs (thus no CT)
How does Liquefactive necrosis appear under the microscope?
Amorphus, granular
What is an abscess filled with? Does it have vascular supply?
Area filled with PMNs.
No vascular supply
How does caseous necrosis appear grossly?
Grayish, whitish or yellowish
What are the two organisms that cause caseous necrosis?
TB
Fungi (especially histoplasmosis)
What does caseous necrosis appear like beneath the microscope?
Granulated material with surrounding giant cells
What does enzymatic fat necrosis look like grossly?
White, chalky
What does enzymatic fat necrosis look like microscopically?
Stuff in fat cells rather than their normal, clear appearance
Potentially basophilic if there is enough Ca
In what disease does enzymatic fat necrosis usually take place? Why?
In pancreatitis
Because lipases produced solely in the pancreas
Why is fat necrosis seen more often in pts with hyperthyroidism?
Increased Ca in the blood activates enzymes
What is fibroid necrosis?
Injury in blood vessels with accumulation of plasma proteins causing the wall to stain intensely eosinophilic
What causes fibroid necrosis?
Antigen-ab complexes activated clotting cascade
What is wet gangrene?
Combination of gangrene with superimposed bacterial infection
Green discoloration around a wound indicates what?
Pseudomonas
What causes reperfusion injury?
lack of enzymes that reduce ROS, leading to a sudden burst of ROS
What are the three things that ROS damage?
Membranes (via lipd radicals)
Protein (abnormal folding)
DNA (mutations)
What are the two findings of reperfusion injury besides increased ROS?
- Expression of cytokines and cell adhesion molecules
2. Activation of complement pathway
What are the proteins that activate apoptosis?
Caspases
What happens to the plasma membrane in apoptosis?
Remain intact, but it is altered such that the cell and its fragments become targets for phagocytes
What are the stages of apoptosis?
- Signal to initiate
- Intracellular signals
- Execution phase via caspases
- Removal of dead cells
What is function of caspases in apoptosis?
Catabolize the cytoskeletons and activate endonucleases
What are the two pro-apoptotic proteins in a cell that form holes in the mitochondria? What does this cause?
Bax
Bak
Causes cyt C to leak out and activate initiator caspases
What is the function of Bcl-2 and Bcl-X?
Block Bax and Bak, thereby inhibiting the apoptosis pathway