Flashcards in Healing and Repair 8-5-15 Deck (21)
What is regeneration replacing damaged cells with, what is scar formation replacing damaged cells with?
regeneration: replicating cells of the same type
scar formation: connective tissue
What do you need to remain intact in order to have regeneration?
connective tissue framework-scaffolding for replacement of residual uninjured cells (cells must have capacity to divide)
What is labile tissue?
lost cells replaced by
-maturation of stem cells
-proliferation of mature cells
Hematopoietic cells of bone marrow
Squamous epithelium of skin, oral cavity, cervix, vagina
Columnar epithelium of GI tract
What is stable tissue?
low, no level of replication
-G0 cell cycle
rapidly divide when stimulated
-G1 cell cycle and beyond
kidney, pancreas, smooth muscle cells, fibroblasts
What are permanent tissues?
terminally differentiated, non proliferative in postnatal life
-brain and heart
What are is the pro and the con of scar formation?
Con-fibrous tissue loss of function-loss of parenchymal cells
Pro-structural stability for injured tissue to continue function
What are important mediators of angiogenesis?
FGFs(fibroblast growth factor)
PDGF(platelet growth factor)
What induces VEGF?
What do fibroblasts do? What are they activated by?
synthesize connective tissue proteins
-growth factors (PDGF, FGF, TGF-B)
What is granulation tissue? What does it consist of?
specialized tissue that fills in defects in organs when non-regenerative cells and or connective tissue framework is destroyed
1. proliferating Fibroblasts (laying down immature connective tissue (collagen type 3))
2. proliferating new blood vessels
-only during attempt to heal destroyed tissue
What is organization? What happens with time?
process of transforming granulation tissue into a dense scar
With time: blood vessels become less prominent, collagen matures (type 3 collagen replace type 1)
What color is mature collagen stain on a trichrome stain?
What are the7 steps to healing of skin wounds?
2. blood clot (fibrin, fibronectin) forms
3. Epithelium regenerates to cover
4. cells proliferate and migrate to defect
a. macrophages-remove debris, secrete cytokines
b. fibroblasts-produce extracellular connective tissue matrix
c. myofibroblasts contract the wound
5.simultaneously capillaries at edge of defect proliferate and extend into the defect under the influence of chemical mediators
6. over weeks to month defect filled with granulation tissue, becomes remodeled to mature collaged( scar)
7. Wound acquires strength through the process
What is healing by first intention?
-clean uninfected surgical incision approximated by surgical sutures
-epithelial regeneration principle mechanism of repair
-minimal contraction of wound
What is healing by second intention?
-large skin wound
-extensive destruction, contaminated infected
-larger clot, more intense inflammation
-wound granulates without closing gap with sutures
-process of healing same
-wound contraction by myofibroblasts
Wound strength at 1 week vs 3 months?
1 week= 10%
WHat is fibrosis?
excessive deposition of collagen and other EMC components in a tissue
How do glucocorticoids affect repair?
anti-inflammatory, inhibit TGF -B production
What three vitamins/minerals help in wound healing?
What is a keloid?
-accumulation of exuberant amount of cartilage
-raised scars, grow beyond wound boundaries
-more common in African Americans