Necrosis Flashcards
what is the order of the 3 events?
necrosis, inflammation, apoptosis.
what is hypoxia/ischemia?
no oxygen cell death
physcial/chemical reasons for cell death?
trauma.
is cell injury reversible or not?
reversible.
is cell death reversible or not?
irreversible.
what happens to cell size during n?
enlarged.
what happens to cell size during a?
reduced,
what happens to nucleus during n?
pyknotic.
what happens to nucleus during a?
fragmented.
what happens to cell membrane during n?
disrupted.
what happens to cell membrane during a?
intact.
what happens to cell contents during n?
digested/leakage.
what happens to cell contents during a?
intact-ish.
what happens to inflammation during n?
subsequent/frequent.
what happens to inflammation during a?
none usually.
necrosis morphology?
- pyknosis
- karyorrhexis
- karyolysis
- cytoplasmic changes
what is pyknosis?
nuclear shrinkage/DNA condenses.
what is karyorrhexis?
fragmentation/nuclear memrbane ruptures.
what is karyolysis?
fading/dissolution of chromatin (DNAases RNAases)
what cytoplasmic changes occur during necrosis?
increased eosinophilia due to binding of eosin to damaged proteins. cells look darker.
what is coagulative n?
- proteins denature and aggregate rather than degrade.
- inflammatory response.
- dead cells/tissue replaced by regeneration
what is liquefactive n?
- enzymic digestion of cellular components?
- dissolution of tissue
what is caseous n?
- end result of tuberculosis infection.
- inflammatory response initiated/phagocytosis.
- cheese-like debris
what is fat n?
- end result of lipases digesting cells.
- acute pancreatitis
- inflammatory response intitiated
what is fibrinoid n?
- fibrin accumualtion.
- inflammatory response initiated.
what is gangrenous n?
- loss of blood supply to limb
- undergoes coagulative necrosis across multiple layers of tissue
- inflammatory response initiated.
what are the potential mechanisms for cell death?
- loss of atp for energy
- loss of mitochondrial function
- loss of calcium homeostasis
- production of reactive oxygen
What are major causes of atp depletion?
-hypoxia/ischemia
why does the lack of atp lead to cell death?
- failure of the na/k pump to work
- na accumulated
- gain of solute is followed by gain of water.
- cell swells
- anaerobic glycolysis increases, so decrease in pH.
- protein synthesis apparatus is damaged.
how does lack of calcium homeostasis lead to cell death?
- atp dependant ca2+ pump doesn’t work, so influx of ca2+.
- activation of ca2+ enzymes.
- activation of proteases, lipases (breakdown of cytoskeleton proteins and phospholipid membranes), endonucleases
how does production of reactive oxygen species lead to cell death?
-ros attack key molecules when uncontrolled.
physiological causes of apoptosis?
serves to eliminate cells that are no longer needed, and to maintain a steady number of various cell populations in tissues.
pathological causes of apoptosis?
eliminates cells that are injured beyond repair without eliciting a host reaction, thus limiting collateral tissue damage.
what pathways are there for apoptosis?
- extrinsic (death receptor pathway)
- intrinsic (mitochondrial)
what activates intrinsic pathway?
- DNA damage (dna damage activates pro-apoptotic factors)
- promotes release of cytochrome c from the mitochondria which activates caspase 9
- caspase 3 is at the effector stage of apoptosis (cleavage and inactivation of cell constituents)
