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Flashcards in Cellular Adaptation Deck (41):
1

pathological adaptation

adaptations occurring as a result of certain stimuli which are not lethal

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cell responses to stimuli/injury

ignore (quiescence), adapt, divide and differentiate, or die

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Describe the stages of cellular response to stress and injurious stimuli

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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

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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

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non-dividing cells/tissues

no or limited capacity to divide such as neurons, cardio myocytes and adult skeletal muscle cells

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embryonic stem cells

derived from blastocysts, can generate an entire organism

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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

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Describe the process of adult stem cell differentiation after injury.

stem cell to commited progenitor to transient amplification to differentiation to replacement

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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

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mitogens, motogens, and orphogens

mitogens - cause cell division

motogens - cause cells to migrate or scatter

morphogens - cause morphological change

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four types of signaling

endocrine, paracrine, autocrine, and intracrine or metacrine

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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

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paracrine

when a cell produces a peptide and releases it into the extracellular space, and then that peptide aacts on adjacent cells locally

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autocrine

when a particular cell produces a growth factor releasing the peptide into the extracellular space

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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

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intracrine or metacrine

new concep, product is generated within the cell and acts on the same cell

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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

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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

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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

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EGF

epidermal growth factor, excreted from submaxillary glands, causes proliferation and differentiation of epithelium

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FGF

fibroblas growth factor, potent mitogen for fibroblasts and endothelium, also a vasculogenic factor

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prolactin

required fro proliferation and differentiation of the breast epithelium during pregnancy as a prerequisite for lactation

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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

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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

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hypertrophic obesity

seen in adults, due mostly to increase in fat cell size

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hyperplastic obesity

seen in children or severe obesity in adults, due to increased fat cell number

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injury in non-dividing tissues

results in replacement by fibrotic scarring

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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

30

involution

a type of physiological atrophy, return to normal size after hyperplasia and hypertrophy, if the causitive stimuli are removed and equilibrium returns back

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ischemic atrophy

atrophy of tissue due to deacrease of blood supply

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pressure atrophy

due to long continued pressure on a tissue leading to decrease in blood supply with atrophy of cells

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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

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metaplasia

change in differentiation from one cell type to another patches of tissue that differn from surrounding normal tissues, reversible

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epithelial metaplasia

the continuous turnover of skin and other epithelia

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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

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glandular metaplasia

refers to a change of the squamous epithelium to glandular epithelium

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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

39

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

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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

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neoplasia

cellular autonomy and uncontrolled growth, irreversible