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60 Cards in this Set
- Front
- Back
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what type of tissues do regeneration
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stable (liver and kidney- compensatory growth) and labile tissues (GI tract, epidermis, hematopoeitic system)
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what two processes make up healing?
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repair (scarring - fibrosis) and regeneration
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scarring definition
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deposition of fibrous tissue and ECM
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when does scarring occur?
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when parenchymal tissues don't regenerate, when injury damages ECM, chronic inflammation
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how does chronic inflammation cause scarring?
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it causes release of cytokines and GF that make fibroblasts proliferate and make collagen
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what is regeneration?
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replacement of parenchymal cells by parenchymal cells of the same type
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what are growth factors
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growth factors are secreted ligands that hook onto receptors in other cells. signal transduction to make cells migrate and proliferate.
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what allows labile cells to regenerate
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stem cells are part of labile cell tissues and they can regenerate as long as stem cells still exist.
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examples of labile cells
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squamous (mouth, vagina, skin), duct (salivary, pancreatic, biliary), columnar (GI and uterus) and transitional epithelium and marrow hematopoeitic cells
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examples of stable cells
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parenchyma of solid glandular tissue (liver, kidney, pancreas), lymphocytes, mesenchyme (bone, cartilage, smooth muscle, endothelium, fibroblasts)
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what are permanent cells examples? how do they heal?
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neurons, nerves, cardiac/striated muscle (skeletal muscle has limited regeneration, in general these undergo compensatory hyperplasia) . scarring
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what are the functions of ECM
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1. organizes tissues 2 substratum for cell adhesion 3 regulates growth movement and differentiation of cells in it...does mechanical support, control of cell growth, maintenance of cell differentiation, scaffolding for tissue renenewal, establishment of tissue microenvironments, storage and presentation of regulatory molecules
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what is ECM made of in general
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three groups of macromolecules make up the interstitial matrix and basement membrane. 1. fibrillar structural proteins 2 hydrated gels 3. adhesive glycoproteins and integrins
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what makes up fibrous structural proteins and what do they do
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fibrous structural proteins: collagens and elastins (tensile strength and recoil)
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what do hydrated gels do?
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resilence and lubrication
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what makes up hydrated gels?
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glycosaminoglycans (GAGS): resilence and lubrication
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what is collagen made up of
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three chains in a triple helix that are crosslinked
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what are the types of collagen that we should know
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type I, II, II, IV, and XI (fibrillar collagens)
IV is sheet collagen VII is anchoring fibrils |
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what collagen types are in mature wounds, which are in immature wounds
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collagen Type I is in mature wounds, III is in first days after healing
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what is elastin made up of
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central core of elastin surrounded by microfibril network. (bad fibrillin in Marfans)
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what does fibronectin do?
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it is an adhesion protein in the ECM that acts as a paperclip
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what does laminin do?
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extends from the cell to attach to the ECM via fibronectin paperclip
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one word to describe cell adhesion proteins
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glue of ECM
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what are the two types of glycosaminoglycans
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proteoglycans (dishbrush) and hyalurononan (large molecule that's good at holding water, good for tissues that are compressed)
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what is the purpose of glycoasminoglycans
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hydrated gels for resilience, lubrication, reservoir for growth factors, regulate connective tissue structure/permeability, modulate cell growth/differentiation
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what makes up proteoglycans
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glycoprotein core with covalently attached glycoasminoglycan chains, hyaluronanan isn't a proteoglycan
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what are the two parts of the ECM
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basement membrane and interstitial matrix
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what is the basement membrane made up of
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type IV collagen, laminin, proteoglycan
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what makes up the interstitial matrix
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fibroblasts make it. it's made up of fibrillar collagen, elastin, proteoglycan, hyaluronan
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what do fibroblasts make
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collagen, elastin, proteoglycans, adhesive glycoproteins
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how does the ECM help in wound healing?
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cells (fibroblasts and macrophages) in ECM secrete growth factors, mechanical support for cell anchorage, scaffold to organize regeneration (critical for organized repair)
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what are the steps of scarring
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1. angiogenesis
2. migration, proliferation of fibroblasts at injury sites 3. remodel fibrous tissue and ECM |
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what is angiogenesis controlled by
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VEGF (vascular endothelial growth factor) and FGF (fibroblast growth factor)
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what controls migration and proliferation of fibroblasts
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TGF-B, PDGF, EGF, FGF, TNF derived from platelets, inflammatory cells, endothelium. fibroblasts then deposit ECM
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granulation tissue is made up of
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angiogenesis vessels and fibroblasts (swimming pool white skin)
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what is needed for would healing
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balance between matrix deposition and degradation needed for effective wound healing
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what is a scar made of
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type 1 collagen, inactive fibroblasts, elastin and other ECM
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what does the remodeling during wound healing?
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metalloproteinases including collagenase
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who secretes collagenase an at what induces it to be secreted
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fibroblasts, macrophages, neutrophils
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what is collagenase formation induced by?
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PDGF, FGF, EGF, TNF
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what is collagenase secretion stopped by?
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TGF-B (transforming growth factor), steroids
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what are the steps of wound healing?
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1. hemostasis
2. inflammation 3. parenchymal and CT cells migrate, proliferate, regenerate 4. granulation tissue forms 5. parenchymal elements remodel 6. ECM remodels |
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what does inflammation do during wound healing
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first step of wound healing. gets rid of inflammation, gets rid of dead tissue, initiates ECM deposition (via growth factors)
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what is the star inflammatory cell during wound healing?
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macrophages: debridement, infection clearance, chemotaxis and proliferation of fibroblasts and keratinocytes, angiogenesis, deposition and remodeling of ECM
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when does granulation tissue appear?
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overlaps with inflammation (which is the first step in wound healing)
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what is the replacement of inflammation by granulation tissue called?
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organization (granulation tissue is pink, soft, granular tissue)
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what are clots?
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clots are combinations of fibrin and RBC
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what is a scab?
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scab is a dehydrated surface clot.
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differences between primary and secondary intention
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more CT needed to fill in defect, more inflammation (greater risk of inflammation caused injury), larger scar that is weaker
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what is the most important cause of a delay in healing?
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infection. prolongs inflammation and causes more tissue damage
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why is vitamin C needed for effective wound healing
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essential for procollagen synthesis (hydroxylation of procollagen)
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what are some nutritional systemic factors that delay wound healing?
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scurvy, varicose veins (significant stasis), decubitus ulcer (ischemia)
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how do diabetes and steroids inhibit would healing?
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diabetes (microangiopathy), steroids inhibit fibrosis by inhibiting metalloproteinases needed for scar maturation
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how does nervous system repair work?
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Nervous system repair: upon injury to nerve cells within the central nervous system, astrocytes become phagocytic to ingest the injured nerve cells. The astrocytes then fill up the space to form a glial scar, repairing the area and replacing the CNS cells that cannot regenerate
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what is brain fibrosis
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gliosis
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what is a keloid caused by
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maturation arrest of collagen assembly
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what is a gut contracture
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when healing in the gut causes a stricture (caused by myofibroblast activity)
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what is a contracture
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excessive contracture with functional, cosmetic disability. due to thickened, shortened collagen bundles
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what is proud flesh?
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excessive granulation tissue that impairs wound healing
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what are adhesions
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granulation tissue grows into a space, then its replaced by a scar.
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