Cell Injuries, Adaption and Aging Flashcards
(30 cards)
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)
atrophy
response to lack of use
metaplasia
typically in fragile types of cells
eg. vitamin A deficiency
dysplasia
increase in poorly differentiated cells
abnormality in formation of a tissue
can precede neoplasia
hyperchromatic nuclei
anicytosis
variation in size
polikocytosis
variation in shape
karyomegaly
large nuclei
simple squamous epithelium
lubrication, diffusion and filtration
blood vessels, lymphatic vessels, alveoli, heart lining
simple cuboidal epithelium
secretion and absorption
secretory ducts of small glands, kidney tubules
simple columnar
absorption, secretion of mucous and enzymes
bronchi, uterine tubes, uterus - ciliated
digestive tract, bladder - non-ciliated
