cell injury Flashcards
cell fate: define and recall examples of hyperplasia, hypertrophy, atrophy, metaplasia and dysplasia; define and compare apoptosis and necrosis
5 cellular adaptations to injury
atrophy, hypertrophy, hyperplasia, metaplasia, dysplasia
define atrophy
shrinkage in size of cell organ because of loss of cell substance (cell number and size both decrease)
example of atrophy
dementia
what is atrophy caused by
malnutrition, poor circulation, poor exercise, loss of nerve supply to organ
define hypertrophy
increase in size of cells, increasing size of organ
example of physiological hypertophy
pregnancy
example of pathological hypertrophy
blood pressure
what is hypertrophy caused by
increased functional demand or hormonal stimulation
define hyperplasia
increase in number of cells, increasing size of organ
example of physiological hyperplasia
menstrual cycle
example of pathological hyperplasia
excess TSH causing thyroid cancer
causes of physiological hyperplasia
hormonal or compensatory
causes of pathological hyperplasia
excessive hormonal or growth factor stimulation
define metaplasia
reversible change where adult cell type replaced by another (e.g. effect of smoking)
examples of physiolocial metaplasia
in cervix, columnar epithelia to squamous and back; in Barrett’s oesophagus, squamous epithelia to columnar and back with acid reflux
define dysplasia
presence of precancerous cells which show genetic and cytological features of malignancy (e.g. high nuclear:cytoplasmic ratio) but don’t invade underlying tissue
example of dysplasia
in some cases Barrett’s oesophagus
necrosis definition
confluent (many adjacent cells) cell death associated with inflammation
when does necrosis occur
when insufficient ATP is present
necrosis pathway
damage to cell membrane → fluid released (incl. enzymes etc.) → attraction of neutrophils → inflammatory reaction
types of necrosis
coagulative, liquefactive, caseous, fat
define coagulative necrosis
cells are dead but can be seen and identified as particular cell type as everything keeps its shape
example of coagulative necrosis
myocardial infarct
define liquefactive necrosis
where the cell dies, becomes a liquid and is entirely drained out
where is coagulative necrosis specific to
brain
define causeous necrosis
when cut, it oozes and appears creamy and “cheesy”
examples of causeous necrosis
pulmonary TB
what is causeous necrosis associated with
granulomas (type of chronic inflammation)
define fat necrosis
fat salts produced, forming deposits
inflammation of pancreas as example of fat necrosis
increased lipase production → acute pancreatisis → triglycerides broken down to glycerol and fatty acids → fatty acids bind to calcium in EC fluid → calcium fat salts produced, forming deposits
define apoptosis
programmed single cell death requiring ATP, with no inflammation
DNA and p53 as cause of apoptosis
DNA irreversibly damaged; cell becomes “stuck” as the p53 tumour suppressor gene prevents proliferation
why is apoptosis preffered
an inflammatory reaction to DNA would damage other healthy cells around it
process of apoptosis
parts of cell bud off → cell membrane never ruptures, instead blebs → contents of cells kept in vesicles → vesicles phagocytosed by macrophages
reasons for apoptosis
embryogenesis, deletion of auto-reactive T cells in thymus, hormone-dependent physiological involution (e.g. menstrual cycle), cell deletion in proliferating populations, variety of mild injurious stimuli causing irrepairable DNA damage
necrosis vs. apoptosis
apoptosis may be physiological, necrosis is always pathological, apoptosis is an active energy-dependent process, apoptosis is not associated with inflammation
define necroptosis
programmed cell death which is energy dependent but associated with inflammation (so halfway house); many causes e.g. viral infections
