Tissue Repair Flashcards
Proliferation of cells and tissues to replace lost structures
Regeneration
Tissue response to injury consisting of regeneration and fibrosis or connective tissue deposition (scar formation)
Repair
Extensive deposition of collagen in the setting of chronic inflammation, severe injury, and permanent damage
Fibrosis (scarring)
Regenerative capacity:
- continuously lost and replace (proliferating of residual cells or maturation of stem cells)
- exhibited by surface epithelium, hematopoietic stem cells
Labile
Regenerative capacity:
- maintained in a state of quiescence (G0 in cell cycle)
- limited capacity to proliferate (except hepatocytes)
- proliferate in response to injury or tissue loss
- exhibited by liver, kidney, pancreas, endothelium, fibroblasts, smooth muscle
Stable
Regenerative capacity:
- terminally differentiated (left the cell cycle)
- non-proliferating
- exhibited by neurons, striated muscle
Permanent
First step of repair by connective tissue deposition, involving the formation of new blood vessels from existing ones via growth factor VEGF
Angiogenesis
(3 steps of repair by connective tissue deposition
- Angiogenesis
- Formation of granulation tissue
- Remodelling of scar)
Second step of repair by connective tissue deposition, involving fibroblasts and loose connective tissue from the extracellular matrix, with continuing angiogenesis and infiltration of infammatory cells (hallmark of repair)
Formation of granulation tissue
(3 steps of repair by connective tissue deposition
- Angiogenesis
- Formation of granulation tissue
- Remodelling of scar)
Third and final step of repair by connective tissue deposition, involving the formation of the fibrous scar, balancing ECM degradation by metalloproteinases and ECM protein synthesis by tissue inhibitorso of metalloproteinases (TIMPs)
Remodelling of scar
(3 steps of repair by connective tissue deposition
- Angiogenesis
- Formation of granulation tissue
- Remodelling of scar)
The “central cell” in tissue repair, producing PDGF, FGF2, and TGF-b
Macrophage
7 factors that impede tissue repair
- Infections
- Diabetes mellitus
- Vitamin C deficiency
- Glucocorticoids (inhibit TGF-b)
- Pressue
- Poor perfusion
- Foreign bodies
Abnormality in tissue repair formed from the inadequacy of granulation tissue formation
Wound dehiscence and ulcer
Abnormality in tissue repair formed from the excessive formation of repair components
Keloids and hypertrophic scars
Abnormality in tissue repair formed from exuberant granulation tissue
Proud flesh
Abnormality in tissue repair formed from excessive wound contraction
Contracture