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wound healing
Restoration of integrity to an injured tissue.
Pathology:
3 phases* of wound healing:
1) initial tensile strength
a) hemorrhage into tissue
b) formation of a fibrin clot
c) fibronectin in extravasated plasma is cross-linked to extracellular matrix components (fibrin, collagen) by transglutaminases
2) remodelling
a) phagocyte (neutrophil, macrophage) recruitment
b) proteolysis & phagocytosis
c) temporary matrix formation from blood proteins
1] proteoglycans
2] glycoproteins
3] type 3 collagen
4] fibronectin
3) definitive scar
a) proliferation
1] fibroblasts
2] endothelial cells
3] smooth muscle
b) granulation tissue
c) wound contraction
d) definitive matrix
-> type 1 collagen
* ref [2] suggests 4 phases, hemeostasis, inflammatory, proliferative, & maturation
2 forms of healing
1) healing by primary intention
a) wounds with apposed edges of healthy tissue
b) minimal tissue loss
c) requires minimal cell proliferation & neovascularization
d) small scar
e) for clean wounds
2) healing by secondary intention
a) wounds with separated edges of healthy tissue
b) gouged wound, significant tissue loss, contaminated wound
c) requires granulation tissue to heal
1] wound contraction
2] cell proliferation
3] neovasculatization
d) wound re-epithelialized from margins
e) collagen fibers in granulation tissue
f) granulation tissue eventually resorbed & replaced by scar tissue
Specific
impaired wound healing; impaired tissue repair
General
healing
References
- Pathology, 2nd ed. Rubin & Farber (eds), JB Lippincott,
Philadelphia, 1994, pg 81-92
- Geriatric Review Syllabus, 8th edition (GRS8)
Durso SC and Sullivan GN (eds)
American Geriatrics Society, 2013
- Williams JZ, Barbul A.
Nutrition and wound healing.
Crit Care Nurs Clin North Am. 2012 Jun;24(2):179-200.
PMID: 22548858
- Geriatric Review Syllabus, 9th edition (GRS9)
Medinal-Walpole A, Pacala JT, Porter JF (eds)
American Geriatrics Society, 2016