Pathoma: Growth Adaptations Flashcards
Adaptation
increase, decrease, or change in stress on an organ
Hyperplasia
increase in number of cells
production of new cells from stem cells
Hypertrophy
increase in size of cells
involves gene activation, protein synthesis, and production of organelles
increased production of cytoskeleton (proteins)
Permanent tissues
do NOT have stem cells can only undergo hypertrophy cardiac myocytes skeletal M. nerve
What can pathologic hyperplasia progress to?
dysplasia and cancer
endometrial hyperplasia–>carcinoma
EXCEPTION: benign prostatic hyperplasia (no risk for cancer)
Atrophy
decrease in stress–>decrease in organ size
occurs via decrase in size and number of cells
occurs via apoptosis- decrease in cell number
2 ways cells decrease in size in atrophy
ubiquitin-proteosome degradation of cytoskleteon
autophagy of cell components
Metaplasia
change in stress–>change in cell type
What kind of epithelium does metaplasia normally involve?
surface epithelium
Why does metaplasia occur?
to adapt cells to be better able to handle new stress
Example of metaplasia
Barrett’s esophagus: esophagus normally lined by squamous epithelium but changes to mucous secreting columnar epithelium like in stomach when acid in stomach goes into the esophagus
How does metaplasia occur?
reprogramming of stem cells
Is metaplasia reversible?
Yes, by removal of the driving stressor
Can metaplasia progress?
Yes, to dysplais and cancer
EXCEPTION: apocrine metaplasia (fibrocytic changes in the breast)
What deficiency can lead to metaplasia?
Vitamin A
night blindness
immune system unable to mature
keratomalacia–>thickening of the conjunctiva of the eye
What tissues can undergo metaplasia?
mesenchymal tissues
bone, blood vessels, cartilage, fat
connective tissues
Myositis ossificans
inflammation of skeletal muscle due to trauma that converts it to bone
looks similar to osteocarcinoma but the bone next to it is normal and there is a distinct separation of the bony metaplasia from the normal bone
Dysplasia
disordered cell growth
proliferation of precancerous cells
What leads to dysplasia?
longstanding pathologic hyperplasia (endometrial hyperplasia) or metaplasia (Barrett’s esophagus)
Is dysplasia reversible?
Yes, with alleviation of inciting stress
if stress persists, can lead to carcinoma (irreversible)
Aplasia
failure of cell production during embryogenesis
Ex: unilateral renal agenesis
Hypoplasia
decrease in cell production during embryogenesis
results in relatively small organ
Ex: streak ovary in Turner Syndrome
