Cellular Adaptation Flashcards
pathological adaptation
adaptations occurring as a result of certain stimuli which are not lethal
cell responses to stimuli/injury
ignore (quiescence), adapt, divide and differentiate, or die
Describe the stages of cellular response to stress and injurious stimuli
continually dividing cells/tussues
skin, gastrointestinal mucosa, respiratory epithelium, and bone marrow
repair results in fully restored tissue
a hyperplastic response - a net gain in cell number
hypoplastic response - net loss in cell number
outcome depedns more on cell proliferation than on cell loss
conditionally dividing cells
hepatocytes, pancreatic acinar cells, kidney, endocrine cells
do not normally divide on a regular basis
possess the capacity to divide when there is an appropriate stimulus
non-dividing cells/tissues
no or limited capacity to divide such as neurons, cardio myocytes and adult skeletal muscle cells
embryonic stem cells
derived from blastocysts, can generate an entire organism
adult stem cells
generate committed progenitor progeny who can function to maintain normal cellular turnover within an orga, or serve to provide regenerative capacity within an organ
Describe the process of adult stem cell differentiation after injury.
stem cell to commited progenitor to transient amplification to differentiation to replacement
two recent discoveries regarding adult stem cells
stem cells undergo asymmetric division of the sister chromatids
tissue microenvironment determines the differentiated fate of the residing stem cell population
mitogens, motogens, and orphogens
mitogens - cause cell division
motogens - cause cells to migrate or scatter
morphogens - cause morphological change
four types of signaling
endocrine, paracrine, autocrine, and intracrine or metacrine
endocrine
“action at a distance”, a hormone synthesized and secreted by hormone-producing cells enters the blood vessel and then acts on target cells/tissues some distance form the source
ectopic hormontes - hormone-like peptides produced by some cancer cells, act like hormones
paracrine
when a cell produces a peptide and releases it into the extracellular space, and then that peptide aacts on adjacent cells locally
autocrine
when a particular cell produces a growth factor releasing the peptide into the extracellular space
autocrine
when a particular cell produces a growth factor releasing the peptide in the tht extracellular space, which then comes back and interacts with the same cell
intracrine or metacrine
new concep, product is generated within the cell and acts on the same cell
TGFalpha and TGFbeta
transforming growth factor
main target of alpha is epithelial cells, also plays a role in liver cell mitosis/liver regeneration
beta acts mostly on a variety of epithelial and mesnchymal cells
VEGF
vascular endothelial growth factor
major regulator of vasculogenesis and angiogenesis
vasculogeneis is responsible for expansion and coalescence of vascular endothelial precursor cells that forms a primary capillary plexus
angiogenesis takes the precursor cells and remodels them into blood vessels
HGF
hepatocyte growth factor, key regulator for liver fgrowth and function, increases when liver mass is decreased, mostly produced by Ito (fat producing cells) cells in the liver
EGF
epidermal growth factor, excreted from submaxillary glands, causes proliferation and differentiation of epithelium
FGF
fibroblas growth factor, potent mitogen for fibroblasts and endothelium, also a vasculogenic factor
prolactin
required fro proliferation and differentiation of the breast epithelium during pregnancy as a prerequisite for lactation
hypertrophy
an increase in the size of an organ or tissue due to enlargement of individual cells without the increase in cell number
usually occurs in organs where proliferation and mitosis are restricted
can be pathological or physiological and is reversible
hyperplasia
an increase in the size of an organ or tissue due to an increase in the number of constituent parenchymal cells
may be physiological or pathological and is reversible
hypertrophic obesity
seen in adults, due mostly to increase in fat cell size
hyperplastic obesity
seen in children or severe obesity in adults, due to increased fat cell number
injury in non-dividing tissues
results in replacement by fibrotic scarring
atrophy
reversible adaptive response on the part of the cell to reduce the size of functional cytoplasm, decrease in cell organelles
characterized by decreased protein and membrane synthesis, increased protein degradation, ubiquitination, autophagy, altered balance between protein synthesis and catabolism
often associate with fibrosis
involution
a type of physiological atrophy, return to normal size after hyperplasia and hypertrophy, if the causitive stimuli are removed and equilibrium returns back
ischemic atrophy
atrophy of tissue due to deacrease of blood supply
pressure atrophy
due to long continued pressure on a tissue leading to decrease in blood supply with atrophy of cells
hypoplasia
reduction in cell number, tissue and organ size are markedly reduced, can be physiological or pathological, occurs as a result of reduced cell proliferation or increased cell loss or both
metaplasia
change in differentiation from one cell type to another patches of tissue that differn from surrounding normal tissues, reversible
epithelial metaplasia
the continuous turnover of skin and other epithelia
squamous metaplasia
transformation of a less resistance mucinous or glandular epithelium to a more resistant stratified squamous type
ex. smoker’s lung often have stratified squamous epithelium replacing the resipiratory epithelium
glandular metaplasia
refers to a change of the squamous epithelium to glandular epithelium
Barett’s esophagus
stratified squamous epithelium of the esophagus is replaced by intestinal columnar epithelium due to gastro-esophageal reflux and/or alcoholism
intestinal tissues is more resistant to acid, but this tissue can become dysplastic and lead to carcinoma
connective tissue metaplasias
transformation or trans-differentiation between mesodermally-derived tissues, possibly from a primitive/stem cell
results in connective tissue such as bone in different tissues ssuch as muscle or tumors
dysplasia
disordered growth and maturation of the cellular components of a tissue, not yet neoplasitc
pleomorphism, hyperchromatism, abundant mitoses, and loss of normal orientation
often reversible
neoplasia
cellular autonomy and uncontrolled growth, irreversible
