Cell injury and fate Flashcards
what happens when there is a lethal cell injury?
cell death
what happens when there is a sublethal cell injury?
may be reversible or progress to cell death
list the different causes of cell injury
1) oxygen deprivation (critical)
2) chemical agents e.g. drugs
3) infectious agents
4) immunological reactions e.g autoimmune
5) genetic defects e.g. chromosomal
6) nutritional imbalances
7) physical agents e.g. bullet wound, radiation
8) ageing
tissue injury can be driven by some of processes
how does a myocardial infarction occur?
blocked blood flow → extreme ischemia → cell death of tissue → infarction
what do the cellular responses depend on?
1) type of injury
2) duration
3) severity
also depends on tissue type (type of cell + status) e.g. gut lining and bone marrow have a higher turn over rate
what intracellular systems are particularly vulnerable to injury?
1) cell membrane integrity -immediate
2) ATP generation - quick
3) protein synthesis - takes a while but has knock on effect on enzymes
4) the integrity of the genetic apparatus (DNA)
when is cellular function lost during cellular injury?
lost before cell death occurs which happens before morphological changes
define “atrophy”
shrinkage in size by loss of cell substance
e.g. dementia = brain atrophy, or at a cellular level, muscle atrophy e.g. if nerve to muscle has been cut
define “hypertrophy”
incr. in size of cell therefore increase in size of an organ
e. g. uterus in pregnancy is an extreme example of hypertrophy – as it is not proliferation the cells just gets bigger
define “hyperplasia”
incr. in no. of cells in organ
- physiological hyperplasia can be either hormonal or compensatory.
- pathological hyperplasia is usually due to excessive hormonal or growth factor stimulation.
e. g. proliferating endometrium such as during menstruation, kidney removal – other kidney gets bigger to compensate with the lack of the other kidney
define “metaplasia”
A reversible change in which one adult cell type is replaced by another
e. g. columnar epithelium in the cervix becomes squamous during pregnancy due to vaginal pH change.
e. g. barrettes oesophagus
define “dysplasia”
Precancerous cells which show the genetic and cytological features or malignancy but not invading the underlying tissue
-pre-cancerous cells that have an increase in nuclear cytoplasmic ratio → nucleus gets bigger without the cell getting bigger
what are different morphological changes associated with reversible injury?
- fatty change e.g. alcohol fat
- cellular swelling
define the term “necrosis”
confluent cell death (whole areas of cells dying) with inflammation
what are the different types of morphological changes associated with irreversible injury?
1) coagulative necrosis
2) liquefactive necrosis
3) caseous necrosis
4) fat necrosis
what happens during coagulative necrosis?
cells keep their shape but there are changes e.g. cells lose their nuclei, cells that are inflammed
what happens during liquefactive necrosis?
liquefied filled spaces especially as brain lacks supporting framework
what happens during caseous necrosis?
“cheesy” texture → no architecture/structure, just granular and there is inflammation
what happens during fat necrosis?
1) lipase activated in the wrong place
2) will start to digest the fat around the pancreas (fatty acids + glycerol) so there is free fatty acids
3) bind to calcium ]
4) cause white spots around the pancreas
define “apoptosis”
programmed cell death
what are the different causes of apoptosis?
1) embryogenesis → development of an embryo e.g. with fingers
2) deletion of auto reactive
3) hormone dependent e.g. menstrual cycle
4) cell death in proliferating populations e.g. skin and gut proliferating all the time and apoptosis is a safe way for cells to die
5) mild injurious stimuli causing irreparable DNA damage → apoptosis
what are the key differences between apoptosis and necrosis?
1) apoptosis may be physiological
2) apoptosis = active therefore requires ATP
3) apoptosis no inflammation
4) apoptosis single cell
5) apoptosis not very severe
- apoptosis→ death of a single cell with no inflammation around it
- necrosis → many cell deaths with inflammation
define “necroptosis”
programmed cell death associated with inflammation
-it is energy dependent like apoptosis but there is inflammation like necrosis
what can cause necroptosis?
eg. viral infections
