Cell injury ๐ธ Flashcards
Homeostasis
steady state
closely maintained
stress on cells results in an attempt at adaptation
three adaptations to increased demand
hyperplasia
hypertrophy
growth receptors
hyperplasia
increase in cell number in response to external stimulus
can be physiological or pathological
reverses on withdrawal of stimulus
physiological example of hyperplasia
breast tissue in puberty
response to loss of tissue
pathological example of hyperplasia
hormonally induced e.g. excess of oestrogen = endometrial hypoplasia
hyperplasia of lymph nodes in response to infectiom
what happens if cells keep growing in a lack of stimulus?
could be cancerous
hypertrophy
increase in cell size
when does hypertrophy often occur?
in conjunction with hyperplasia
in isolation in non-dividing cells (e.g. skeletal muscle)
in response to mechanical stress
when does hypertrophy become pathological?
when heart/muscle cannot function
requires more blood supply
can cause heart failure
growth receptors
stress growth factors lead to cell division
to increase cell divisionโฆ
produce more growth factors and growth factor receptors
three categories of growth factor receptor
receptors with intrinsic tyrosine kinase activity
7 transmembrane G protein coupled receptors
receptors without intrinsic tyrosine kinase receptors
Atrophy
reduction in cell size, can be physiological or pathological
physiological examples of atrophy
embryological structures
post-menopausal uterus
pathological examples of atrophy
decreased workload
blocked blood supply
loss of innervation