8: Necrosis and Apoptosis 1 Flashcards
normal cell is in what state? injury is what?
steady state aka homeostasis. injury: any stimulus bringing changes in cell physiology or anatomy
injury: reversibility? adaptation?
injury can be reversible or irreversible. irreversible injury results in cell death. adaptation results from changes in a cell due to reversible injury
the pathway from steady state to cell death?
injury agent: then get adaptation, then reversible injurious phase, then irreversible injurious phase, then cell death
two main events that trigger cells to die?
killed by injurious agents to triggered to commit suicide
injurious forces: examples of external and internal factors?
external: physical agents, lack of oxygen, chemical and infections agents. internal: immunologic, genetic, metabolic factors
2 types of programmed cell death
apoptosis. non apoptotic PCD.
cells that die due to external forces primarily undergo what three types of death?
necrosis. parthanatos (PARP1). autophagy.
when does PCD occur?
normally in developing and mature tissue: can be physiologic or pathologic
most modes of cell death occur ___, ___, ___
independently, sequentially, and/or simultaneously
necrosis is?
dramatic and very rapid form of cell death in which every compartment of the cell disintegrates
necrosis: characterized by? which causes 4 things?
dysregulation of ion homeostasis = cell swelling, dilation of mitochondria and ER, formation of vacuoles in cytoplasma, activation of proteases
necrosis: activates what proteases
calpains and cathepsins B + D (lyosomal proteases) which will cause cell degradation
mitochondrial damage can do what? necrosis?
activate proteases like caspases, and cytochrome c release. not necessary for necrotic cell death
during necrosis: what happens in the nucleus? what happens to energy?
chromatin clumps. nuclear membrane disrupted. gene transcription and protein synthesis stops. ATP rapidly depleted (and no energy = ion gradients disrupted)
necrosis: what finally happens to the cells? then cells around it?
cells lyse, spill contents into extracellular fluid. contents can damage neighbouring cells, causes inflammatory response
can cell undergo only necrosis or apoptosis?
there are very few cell death triggers that are capable of inducing only N or A
what determines whether a cell undergoes A or N
the intensity and duration of death-inducing stimulus. severe/sustained = N. less severe/transient = apoptosis.
4 types of necrosis
coagulative. liquefactive. caseous. fat.
most common form of necrosis = ? occurs where? results from?
coagulative necrosis. occurs in solid internal organs like heart, kidney, adrenal tissue. results from sudden and severe ischemia
coagulative necrosis: what happens (2)? what does it look like (2)? finally what happens?
inactivation of hydrolytic enzymes. proteins are denatured. only outline of cells can be seen. boiled meat appearance. eventually, macrophages phagocytose dead tissue, area is replaced with collagenous tissue.
liquefactive necrosis: characterized by? what does it look like?
dissolution of tissue: necrotic area is soft and fluid filled, no cell architecture remains
liquefactive necrosis: what happens (cellularly)? results from? occurs during?
infiltration of neutrofils. results from enzymatic degradation of tissue. brain ischemia
caseous necrosis: what? appearance? when does it occur?
a form of coagulative necrosis, with limited liquefaction. necrotic tissue has appearance of cheese. tuberculosis.
fat necrosis: due to? is a type of?
action of enzymes, followed by formation of complexes with calcium. is a type of liquefactive necrosis, specialized to fat.
fat necrosis: what do you see? when does it happen (ex)?
focal outlines of necrotic fat cells, surrounded by inflammation. ex: pancreatitis.
