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92 Cards in this Set
- Front
- Back
What is the difference between regeneration and repair?
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regeneration refers to plaement of lost structures (hepatocytes). repair is some regeneration, but also scar tissue
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What is fibrosis?
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deposition of collagen that occurs during persistent injury or infection.
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What are terminally differentiated cells?
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cells that cannot differentiate into anything further
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What are labile tissues?
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continuously dividing tissues
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What are quiescent (stable) tissues?
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tissues that are normally very slowly proliferating, but can be increased by stimulus
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What are "permanent" tissues?
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non-dividing tissues; out of the cell cycle (e.g. neurons
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What cells allow for skeletal muscle regeneration?
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satellite cells
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What type of cells are skeletal muscle? (continuous, quiscent or non-dividing)?
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non-dividing
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What type of cells are hepatocytes? (continuous, quiscent or non-dividing)?
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quiescent. normally don't proliferate much, but if the liver is partially removed, they increase proliferation
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In obligatory asymmetric replication by stem cells, what are the 2 cell products after division?
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one stem cell retains its ability to serve as a stem cell. the other enters a differentiation pathway
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In stochastic differentiation by stem cells, what are the 2 cell products after division?
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either both cells differentiate or both cells remain stem cells
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Which has a greater potential for differentiation (can become more things)? pluripotent or multipotent cells?
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pluripotent is less differentiated and can become anything. a multipotent cell is more restricted
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What is transdifferentiation?
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change in lineage commitment of a stem cell
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What are induced pluripotent stem (iPS) cells?
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differentiated stem cells become stem cells by inducing embryonic stem cell genes/signals/transcription factors
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What cells regulate stem cell renewal and progeny cell formation for somatic cells?
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niche cells for particular areas of the body
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Embryonic cells are from what part of the early embryo?
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inner cell mass of blastocyst (pluripotent)
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What is the function of the "Nanog" gene in embryonic stem cells?
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prevent differentiation
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4 major transcription factors induced in iPS cells and found naturally in embryonic stem cells?
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Oct 3/4, SOX-2, c-myc, Klf4
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What are transit amplifying cells?
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from adult somatic stem cells and give rise to progenitors
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What does "developmental plasticity" refer to?
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the ability for cells to transdifferentiate. cells can change their lineages during development, hence the word "plasticity"
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2 types of stem cells found in bone marrow?
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Hematopoietic stem cells and marrow stromal cells
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What are "oval cells"?
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hepatocyte progenitors
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Do neurons regenerate in adult brains?
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apparently they do. neural precursor cells have been found in multiple locations of the brain
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3 areas where stem cells are found in epidermis
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hair follicle, interfollicular surface epidermis, sebaceous glands
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Skin epidermis and intestinal epithelium proliferation/differentiation is regulated by what 2 pathways?
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Wnt pathway and inhibition of BMP (bone morphogenic protein) pathway
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Skeletal muscle does not divide, but do regenerate. How do we get new skeletal muscle?
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satellite cells proliferate ("notch" signaling) and become new skeletal muscle cells
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Where are "limbal stem cells" found?
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between cornea and conjunctiva
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Where is the major checkpoint/restriction point in the cell cycle?
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G1/S transition
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What proteins regulate the cell cycle?
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cyclins, CDKs (cyclin dependent kinases)
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How do CDKs progress a cell through the cell cycle?
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phosphorylating proteins that regulate the cycle (e.g. RB protein)
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Describe the role of RB (restinoblastoma) protein in regulation of the cell cycle.
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RB protein is usually bound to the E2F transcription factor and prevents the cell cycle. CDK phosphorylates it and releases it, activating E2F = transcription = cell cycle
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With regard to the cell cycle, what is senescence?
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damaged cells enter G0 or apoptosis to prevent further damage
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Epidermal Growth Factor (EGF) uses what type of receptor?
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intrinsic tyrosine kinase receptors
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Function of hepatocyte growth factor?
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stimulate hepatocyte mitosis
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PDGF function
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stimulate clotting and bring inflammatory cells (macrophges etc.) to the site of clotting for wound healing and inflammation
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VEGF function
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vasculogenesis (new blood vessels) and angiogenesis (branching blood vessels). also increases endothelial permeability during inflammation
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VEGF uses what type of receptors
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tyrosine kinase
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Fibroblast growth factor is released to promote what types of general activity?
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wound repair, angiogenesis, hematopoiesis, development
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TGF-B uses what receptors?
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serine threonine kinase receptors (Smad pathway)
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TGF-B inhibits growth of what cells?
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most epithelial cells. less TGF-B = more tumor risk
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TGF-B main function
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promote fibrogenic changes/tissue repair. more fibroblasts, less collagen degrading, less proteases
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What is autocrine cell signaling?
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cells signal themselves to produce a product/react
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What is paracrine cell signaling?
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cells release a signal into interstitial fluid and nearby cells respond
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What is endocrine cell signaling?
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cells release hormones into bloodstream that all cells can respond to (if they have the receptors for it)
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TGF-A uses what type of receptor?
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tyrosine kinase. (TGF-B uses serine-threonine kinase)
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Describe the prototype pathway for a receptor with intrinsic tyrosine kinase activity.
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hormone binds, receptor dimerizes, receptor, auto-phosphorylates, GRB2 binds SOS binds RAS binds RAF/MAPK. kinase cascade occurs
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Function of PLC (phospholipase C)
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convert PIP2 into IP3 and DAG
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Function of IP3
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binds sarcoplasmic reticulum and release calcium into cytosol. this calcium now signals more pathways
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Function of diacylglycerol (DAG)
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activate Protein kinase C
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Function of PI3 Kinase
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convert PIP2 into PIP3 to help Protein kinase B/Akt pathway
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Growth hormone, immune cytokines and prolactin uses what type of receptor?
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JAK/STAT (recruit tyrosine kinase)
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Describe the JAK/STAT pathway
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Hormone binds, JAK recruited, phosphorylation to bind and activate STATs. STAT dimerizes and enters nucleus to regulate transcription
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Which type of receptors signal a cAMP dependent cascade?
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heptahelical G-protein receptors
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Where are steroid hormone receptors found on/in a cell?
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in cytosol or in the nucleus
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How do activated steroid hormone receptors regulate transcription?
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by binding to Hormone Responsive Elements on the DNA
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What is compensatory hyperplasia in the liver?
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After liver lobe removal, the lobes still remaining proliferate to regenerate liver cells
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During compensatory growth of the liver after partial resection, what cells give rise to the new hepatocytes?
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the normal remaining hepatocytes (once quiescent) will now replicate a few times to create more new hepatocytes, then return to quiescence. Contrary to popular belief, stem cells/progenitors are not involved in this process
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3 major groups found in ECM
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Collagen fibers, adhesive proteins, proteoglycans
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Most common protein in the animal world.
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Collagen
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Collagen type found in the basement membrane
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4, form sheets instead of fibers
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Type 2 collagen is mostly found in ...
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cartilage
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Why does low vitamin C lead to scurvy or poor wound healing?
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vitamin C is needed for hydroxylation of procollagen during collagen I synthesis. without hydroxyl groups, the collagen is less stable due to less hydrogen bonding
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Marfan's syndrome is characterized by a defect in what protein?
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fibrillin, a major component of elastin
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Why do patients with Marfan's syndrome have aortic dissection?
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aorta has lost is elasticity and cannot expand during high systolic pressure so it ruptures
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Cadherins, integrins and selectins are part of what family of the ECM?
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cell adhesion molecules
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2 major components of basement membranes?
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collagen 4 and laminin
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How does the ECM work to regulate cell function?
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the integrins and receptors can send signals to the nucleus
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Contact inhibition is regulated by what proteins in the ECM?
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catenins and cadherins
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Function of proteoglycans
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made up of GAGs which hold water. proteoglycans lubricate and resist/cushion forces
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Why would metalloprotesases be needed during angiogenesis?
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to degrade the endothelial basement membrane to branch a new vessel
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In a patient withe recent ischemia, what do we expect to see with regard to their EPC (endothelial precursor cells)?
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high levels, suggesting angiogenesis is occurring
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Blockage of DLL4 (Delta like ligand) during angiogenesis has what effect on proliferation?
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increases
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Blockage of DLL4 (Delta like ligand) during angiogenesis has what effect on sprouting?
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increases
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Blockage of DLL4 (Delta like ligand) during angiogenesis has what effect on vascular organization?
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decreases
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Major function of DLL4 during angiogenesis
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orientation /organization of newly formed vessels
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Blockage of VEGF during angiogenesis has what effect on proliferation?
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decreases
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VEGF is regulated by HIF-1. What is HIF-1?
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hypoxia induced factor released during hypoxia
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Once a new blood vessel is formed, what do tie2, Ang1/2 need to do?
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stabilize the weak vessel
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3 phases of cutaneous wound healing
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inflammation, proliferation, maturation
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Purpose of a blood clot during wound healing.
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stop bleeding and serve as scaffold for tissue repair/ inflammatory cells
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Which type of wound would be more likely to have granulation tissue? primary or secondary union?
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secondary union = more tissue damage than primary. more tissue damage = more granulation tissue to repair the tissue
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Most important fibrogenic agent
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TGF-B
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What is wound contraction?
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occurs to close larger wounds on the surface; myofibroblasts and actin do this
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What comes first? Granulation tissue or scar?
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granulation tissue
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The replacement of granulation tissue with a scar is called...
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connective tissue remodeling; ECM will be made and destroyed
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How can nutrition affect wound healing?
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poor vitamin C = bad collagen
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How can infection impede wound healing?
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persistent inflammation
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What is wound dehiscence?
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opening of a healing wound due to poor granulation tissue/scar formation
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What is a keloid?
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a hypertropic scar due to high tissue healing;
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What is wound contracture?
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exaggerated healing process resulting in deformaties
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Tissue repair is stimulated by macrophages activated (classically or alternatively)?
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alternatively (by IL-4, IL-13)
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Function of osteopontin (OPN)
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promote wound healing; mediates myofibroblast differentiation by TGF-B
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