Cell Adaptation Flashcards
two type of stimuli on cells
- stress stimuli (increased demand)
2. injurious stimuli
cell reaction to each
- stress s.: adaptation
2. injurious s.: cell injury
stimuli for adaptation response
Increased demand.
Decreased nutrients.
Chronic irritation.
type of cellular adaptive response
functional response &
structural response. new STEADY state is achieved. cell survives
eg of cellular adaptations to stress
hyperplasia hypertrophy atrophy metaplasia (abnormal change in the NATURE of a tissue) * all reversible
meaning of hypertrophy
increase in SIZE of cells (thus increase in SIZE of ORGAN)
causes for hypertrophy
Physiologic - uterus in pregnancy
Pathologic - myocardium in hypertension
meaning of hyperplasia
increase in NUMBER of cells (thus increase in SIZE of ORGAN)
* hypertrophy and hyperplasia often occur together in response to same stimulus
Physiological causes for hyperplasia (2 categories)
Hormonal - breast growth (puberty/pregnancy)
Compensatory - after partial liver resection
Pathological causes for hyperplasia
due to excess hormones OR growth factors
eg. Endometrial (lining of the uterus) hyperplasia
atrophy
reduction in size AND number of cells (thus decreased organ size)
causes for atrophy
disuse (fracture)
denervation (paralysed pt)
decreased blood supply
decreased nutrition/hormones
metaplasia
ADAPTIVE substitution of one cell type w another (the latter usually better suited to withstand adverse environment)
* REVERSIBLE however: if irritant PERSISTENT = can induce malignant transformation
causes for metaplasia
chronic irritation
eg #1 of metaplasia
smokers: columnar to squamous epithelium (lining of air tracts). SE more resistant to irritant but does not secrete mucous like columnar.
