Cell Injury III Flashcards
What is the definition of necrosis?
Accidental cell death: the morphologic changes of living tissue following cell death that result largely from the degradative action of enzymes.
What are the six types of necrosis? Which one is most common?
- Coagulative (most common)
- Liquefactive
- Gangrenous
- Caseous
- Fat
- Fibrinoid
What type of necrosis results from infarcted tissue?
Coagulative. Unless in the CNS (ischemic stroke) –> liquefactive.
What characterizes coagulative necrosis?
Tissue architecture is preserved for several days due to denatured enzymes. Cells have increased eosinophilia and are anucleate. Inflammatory cells invade to phagocytize the dead tissue.
What causes liquefactive necrosis?
Bacterial and fungal infections that recruit leukocytes that enzymatically digest infected cells, “liquefying” the tissue. Cells that die of hypoxia in the CNS undergo liquefactive necrosis for some reason.
Pus from bacterial infections is characteristic of what type of necrosis?
Liquefactive
What is gangrenous necrosis?
Cell death in a limb due to loss of blood supply. It is a type of coagulative necrosis, and if combined with bacterial infection can be a combination of coagulative and liquefactive necrosis - called “wet gangrene.”
What is caseous necrosis? What is the most common cause?
TB is most common cause. Cellular architecture is lost, tissue takes on a cheese-like appearance and is often enclosed within an inflammatory border.
What is fat necrosis?
Death of adipose cells usually as a result of enzymes such as pancreatic enzymes that leak into the peritoneum. Fatty acids released combine with calcium to form chalky white areas of saponification.
What is fibrinoid necrosis and what causes it? Is it the same this as fibrinous inflammation?
Visible by light microscopy, result of type III hypersensitivity reaction (complement complexes stuck in blood vessels). Vessel walls have increased eosinophilia.
Not the same as fibrinoid inflammation - that is when cell damage allows for leakage of fibrinogen into spaces like the pericardium, which polymerizes to fibrin in the pericadium.
Which two concurrent protein processes occur during necrosis?
Enzymatic degradation and denaturation of proteins
What is a Councilman body?
Apoptosis of a liver cell due to viral infection.
What is phosphatidyl serine’s role in apoptosis?
It flips to the outer plasma membrane to signal “eat me.”
Name an example of an extrinsic apoptotic pathway.
Fas-Fas ligand and TNF-alpha
Name an example of an intrinsic apoptotic pathway.
Mitochondrial activation of pro-apoptotic proteins
