Pathology: cell death Flashcards
what are the 2 types of cell death
necrosis and apoptosis
briefly describe necrosis
always pathological and requires no energy
what are the different types of necrosis
coagulative, liquefactive, caseous
briefly describe coagulative necrosis and an example of when it occurs
preserved cell outline filled with necrosis
i.e. in heart muscle following an MI
briefly describe liquefactive necrosis and an example of when it occurs
no structure remains, space filled with viscous liquid - pus if infective
i.e. in brain following ischaemic stroke
briefly describe caseous necrosis and give an example of when it occurs
area of necrosis surrounded by granulomatous inflammation
classically seen in TB
briefly describe apoptosis
programmed cell death in response to a signal, requires energy, can be physiological of pathological
when does apoptosis occur physiologically
normal growth(i.e. loss of webbed fingers)
loss of self reactive lymphocytes
hormonally regulated processes(e.g. menstrual cycle)
when does apoptosis occur pathologically
as a response to injury
e.g. radiation, chemotherapy, cancer, viral infection
how are cells killed in apoptosis
via caspases that cleave DNA
briefly describe the extrinsic pathway of apoptosis
death receptor initiated pathway, cell membrane receptors with death domain
i.e. Fas (recognises and kills self reactive lymphocytes) or TNF( bind and activate caspases)
briefly describe the intrinsic pathway of apoptosis
loss of growth signals
results in replacement of anti-apoptotic molecules on mitochondrial surface with Bak and Bax, increase permeability of mitochondria, release proteins that stimulate caspases
