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18 Cards in this Set
- Front
- Back
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In regards to proliferating potential, what categories can cells be put into?
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- Stable (hepatocytes, fibroblasts, endothelium) multiply when needed
- Labile (squamous epithelium) multiply constantly) - Permenant (neurones, cardiac and skeletal muscle) dont multiply |
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What is EGF?
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Epidermal growth factor
Stimulates keratinocytes and fibroblast to proliferate. Also stimulates keratinocyte migration and granulation tissue formation. |
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What is TGF?
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Transforming growth factor (alpha and beta)
Alpha stimulates replication of hepatocytes and most epithelial cells Beta is fibrogenic and chemotactiv for macrophages, fibroblasts and smooth muscle |
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What is PDGF?
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Platelet derived growth factor
Causes migration and proliferation of smooth muscle, fibroblasts and macrophages |
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What is FGF?
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Fibroblast growth factor
Involved in angiogenesis and wound repair. Chemotactic for fibroblasts and stimulates fibroblasts to proliferate |
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What is VEGF?
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Vascular endothelial cell growth factor
Increases vascular permeability and causes endothelial cells to undergo mitosis. Also involved in angiogenesis |
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What are the functions of the ECM?
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ECM (extracellular matrix)
- Provides turgor to soft tissue - Provides minerals to give rigidity - Mechanical support - Controls cell growth (integrin signalling) - Maintenance of differentiation - Maintains scaffold needed for tissue renewal - Establishment of microenvironments |
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What are the 3 groups of macromolecules that make up the ECM?
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1. Fibrous structual proteins (collagens and elastins) provide tensile strength and recoil
2. Adhesive glycoproteins (fibronectin and laminin) connect matrix elements to cells 3. Proteoglycans and hyaluronan provide resiliance and lubrication |
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How does fibrosis occur?
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If rissue injury is severe of chronis and results in damage to both paranchymal cells and the stromal framework, then healing can not be accomplished by regeneration. Collagen and other ECM components are deposited forming a scar. This is a fibroproliferative response that patches rather than restores tissue
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What stages does repair of connective tissue consist of?
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1. Inflammaiton
2. Angiogenesis 3. Migration and proliferation of fibroblasts 4. Scar formation 5. Connective tissue remodelling |
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What does the extent of repair and regeneration depend on?
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- Proliferative capacity of the cells in the tissue
- The integrity of the ECM - The resolution of chronicity of the injury |
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What is the difference between vasculargenesis and angiogenesis?
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Vasculargenesis is the assembely of blood vessels during embyonic development (network established by angioblasts and endothelial cell precursors)
Angiogenesis is blood vessel formation in adults |
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What are the two main mechanisms of angiogenesis?
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- Capillary sprouting. Vasodilation (NO) and increased permeability (VEGF) is followed by proteolytic degradation of the basement membrane by MMPs. Then endothelial cells migrate towards angiogenic stimuli and proliferate and mature. The recruitment of periendothelial cells form mature vessels.
- Recruitment of EPC (endothelial proginator cells) from bone marrow. The movement of these cells is called homing |
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What stimulates fibrosis?
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Platelets, endothelial cells and macrophages release FGF, EGF, PGDF which all activate and increase proliferation of fibroblasts
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What systemic factors influence healing?
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- Nutrition (vit C and protein deficienty can retard healing)
- Metabolic status (diabetes impedes healing) - Circulatory status (any venous abnormalities causing inadequate blood flow) - Hormones (glucocorticoids have anti inflammatory effects and inhibit collagen synthesis) |
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What local factors effect wound healing?
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- Infection (causes persistant tissue injury)
- Mechanical (early motion that seperates edges of wounds) - Foreign bodies - Size/location/type (wounds in highly vascularised places heal faster) |
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What is a keloid scar?
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Keloid scars occur when there is excessive formation of wound healing repair components. Initially its comprised of type I collagen but later turns into type III. It is a result of overgrowth of granulation tissue
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What are contractures?
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Tightening of skin after a burn. Normal part of wound healing but can comprimise the movement of a joint. Occur commonly on palms, soles and anterior thorax
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