Cell Injuries, Adaption and Aging Flashcards
Cellular injury due to…
anything that disrupts cellular homeostasis
Basic mechanisms of cell injury (4)
- ATP depletion
- Permeabilisation of membranes
- Disruption of biochemical pathways (especially protein synthesis)
- DNA damage
ATP depletion caused by…
hypoxia/anoxia
toxins
Permeabilisation of cell membranes caused by…
hypoxia/anoxia
reactive oxygen species (free radicals)
Disruption of biochemical pathways caused by…
hypoxia/anoxia
reactive oxygen species (free radicals)
DNA damage caused by…
endogenous causes
- reactive oxygen species (free radicals)
- replication errors
exogenous causes
- UV
- Xrays and gamma rays
- plant toxins
- viruses
Hypoxia/anoxia, mechanism of cell injury…
- O2 needed to produce ATP - work sodium and potassium pumps
- increased osmotic pressure –> more water into cell
- cell rupture
visualise using light microscope - swollen cytoplasm, bigger cell
Visible changes of injured cells…
- swollen
- cytoplasm vacuoles
- darkened colour (hypereosinophilia)
- particularly apparent in hepatocytes and renal tubular epithelial cells
Fatty change (hepatic lipidosis), mechanism of cell injury…
- most in hepatocytes
- lipid enters cells as free fatty acids - used to make cholesterol and phospholipids and ketones for energy
- more used to make triglycerides
- if hypoxia –> triglycerides accumulate (need ATP to convert to lipoprotein to leave cell)
Fatty change, visible changes…
- liver may look normal
- may be enlarged past costal arch
- may be paler pink and lobular
- hypoxic damage to central hepatocytes - cloest to veins
- if cut may bulge and feel greasy
Outcomes of cell injury (4)
- repair
- adaption - if low grade injury
- senescence - stop replicating - if not reparable
- death - programmed (apoptosis)
cell adaption happen when…
a cell is exposed to chronic stressor
adaption mechanisms (5)
hypertrophy - increase in cell size, increased number and size of organelles
hyperplasia - increase in number of cells
atrophy - decrease in cell size
metaplasia - change from one differentiated cell type to another - same germ layer
dysplasia - abnormal differentiation with features of cellular atypia
hypertrophy
in post mitotic cells - can’t replicate
response to increased work load
hyperplasia
response to increased stimuli (often hormonal)
