Cellular Adaptations and Accumulations Flashcards
adaptation
state between the normal, unstressed cell and the injured over-stressed cell. new but altered steady state
reversible
changes in size, number, phenotype, metabolic activity or functions of cell in response to changes in their environment
physiological adaptation
responses of cells to normal stimulation by hormones or endogenous chemical mediators
pathological adaption
can share same underlying mechanisms, allows cells to modulate their environment and escape injury
hyperplasia
increase in number of cells
metaplasia
change in cell type (to another normal type of cell, but it’s a different type)
hypertrophy
increase in size of cells, but not number
examples of physiologic hypertrophy
weight lifter
pregnant uterus
examples of pathologic hypertrophy
cardiac enlargement that occurs with hypertension
3 types of signals invovled with hypertrophy
mechanical triggers
vasoactive agents
growth factors
cells that go into hyperplasia must be capable of what
replication
hormonal hyperplasia
increase in functional capacity of tissue when needed (breast during pregnancy)
compensatory hyperplasia
increased tissue mass after damage of resection
most cases of pathogolic hyperplasia is due to what
excessive hormones or growth factors acting on target cells
examples of pathologic hyperplasia
endometrial hyperplasia, BPH
how does hyperplasia happen
growth factor driven proliferation of mature, and sometimes increased output of new cells from tissue stem cells
causes of atrophy
decreased workload loss of innervation loss of blood supply inadequate nutrition loss of endocrine stimulation pressure
What does atrophy result from
decreased protein synthesis, increased protein degradation
Degrations occurs mainly by what
ubiquitin-proteasome pathway
What is autophagy
starved cells eat their own components to find nutrients and survive
What happens if cell debris in vacuole resists digestion
increasd number of autophagic vacuoles and membrane bound residual bodies (lipofuscin)
When does metaplasia happen
cells that are sensitive to a particular stress are replaced by cells better able to withstand the stress
How does metaplasia happen
happens from epithelial stem cells through genetic reprogramming
example of metaplasia
bronchi in smokers - replacement of ciliated columnar cells with strtified squamous epithelial cells
Why can metaplasia be bad
it can induce cancer
Metaplasia is brought about by singals generated by what
cytokines, growth factors, extracellular matrix components
dysplasia
disorder growth, most commonly seen in squamous epithelial cells following chronic injury
What does dysplasia look like
variations in size and shape of cell
disorderly arrangement within the epithelium
nuclear changes
what specific nuclear changes take place in dysplasia
enlargement, irregular borders, hyperchromasia of individual cell nuclei
