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18 Cards in this Set
- Front
- Back
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1. By what two processes does repair of tissue occur?
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1. Regeneration
-replacement of injured cells by cells of the same type **no trace of residual injury 2. Replacement by CT (scarring) -injured tissue cannot replace itself and/or CT matrix has been severely damaged |
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2. What are labile tissues?
How are the cells in these tissues? What are examples? What happens to these tissues after injury? |
Continuously dividing tissues
Cells are continuously being lost and replaced by maturation from stem cells and proliferation of mature cells Hematopoietic cells and surface epithelia Tissues can readily regenerate after injury so long as pool of stem cells is preserved |
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3. How are the cells of permanent tissues?
What are examples? How is repair in these tissues? |
Cells in these tissues are considered to be terminally differentiated and non-proliferative is postnatal life
Nerve cells and skeletal/cardiac muscle cells Repair in these tissues is dominated by scarring **No ability to regenerate in heart and brain **Some regenerative capacity in skeletal muscle |
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4. When growth factors bind to specific receptors activating a signal transduction system what is the net result?
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1. Relieve blocks on cell cycle progression
2. Prevent apoptosis 3. Enhance synthesis of proteins necessary for mitosis6 |
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5. How do labile tissues regenerate?
What type of regeneration do tissues like pancreas, adrenal, thyroid and lung tissue composed of stable cell populations undergo? What is the exception? Why is regeneration disrupted if the tissue is damaged by infection or inflammation? |
Via stem cells
Limited regeneration Liver Underlying CT framework of tissue is destroyed **scarring typically accompanies the repair in this case |
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6. What are the four component in the process of repair by connective tissue?
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1. Angiogenesis
2. Migration and proliferation of fibroblasts amongst the newly forming vessels 3. Deposition of new ECM by fibroblasts 4. Maturation and organization (remodeling) of the increasingly fibrous tissues |
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7. What occurs during angiogenesis?
Once there is increased permeability what do the endothelial cells do? How is a porous tube formed? |
1. Vasodilation in response to NO
2. Increased permeability of vessels by VEGF Migrate toward the site of injury through the disrupted ECM Proliferation of endothelial cells behind the leading from of migrating cells |
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8. What is granulation tissue?
What is stimulating the fibroblasts to proliferate? |
Admixture of endothelial cells and fibroblasts
Growth factors (PDGF, TGF-beta, FGF) **also stimulate fibroblasts to migrate into the site of injury and co-mingle w/ the blood vessels |
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9. As healing progresses and proliferation of cells decreases what role do fibroblasts assume?
During this time how is the ECM remodeled? (three things) |
Synthetic role --> increased ECM deposited
1. Diminished amounts of hyaluronic acid 2. Increased amounts of fibrillar collagen 3. Vascularity also diminishes w/ time |
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10. What is the end product of connective tissue repair?
What does the scar consist of? What is TGF-beta? What are two effects of TGF-beta? |
Scar
Consists of dense fibrous, largely avascular tissue Potent fibrogenic inhibit 1. Inhibits lymphocyte proliferation 2. Strong anti-inflammatory effects |
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11. What is healing by first intention?
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Least complicated example of wound healing which involves a clean, uninfected surgical incision closed w/ sutures
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12. In healing by first intention what is there limited damage to?
(three things) What does the incision fill with? |
1. Epithelium
2. Basement membrane 3. CT Fills w/ fibrin clot and plasma proteins so a scab forms |
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13. Within 24 hrs of healing by first intention what happens?
When is a basement membrane deposited? |
Neutrophils have migrated into fibrin clot and epithelium has become thicker at wound edge due to mitotic activity
Within 24 - 48 hours by epithelium that has migrated under the fibrin clot |
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14. By day 3 what has happened?
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1. Neutrophils replaced macrophages removing tissue debris
2. Granulation tissue invades into incision site 3. Epithelium over wound is continuous and thickening |
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15. By day 5 what has happened?
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1. Granulation tissue fills incision
2. Angiogenesis is maximal 3. Epithelium back to normal thickness and architecture |
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16. What happens during the second week?
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Fibroblasts and collagen increase w/ edema
Leukocytes and vascularity much in decline |
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17. What is noticeable by the end of the first month?
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Scar
**present w/ some fibroblasts and devoid in inflammatory infiltrate |
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18. How does healing by second intention differ from healing by first intention?
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1. Larger defect has more necrotic debris and exudate that must be removed and inflammation is generally more intense
2. Much larger amounts of granulation tissue are produced 3. Wound contraction mediated by myofibroblasts is much more notable |
