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12 Cards in this Set
- Front
- Back
Healing by first intention
events within within 24 hrs. 4 events |
neutrophils appear at margins of incision, moving toward fibrin clot
- epidermis at cut edges thickens as a result of mitotic activity of basal cells - spurs of epithelial cells from edges migrate and grow along cut margins of dermis depositing basement membrane - fusion of epithelial cells at midline beneath the scab surface |
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Healing by first intention
events by day 3. 4 events |
- neutrophils largely replace by macrophages
- granulation tissue progressively invades incision space - collagen fibers are present in the margin of the incision - epithelial cell proliferation continues, thickening epidermal covering layer |
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healing by first intention events by day 5
5 events. |
- incisional space is filled with granulation tissue
- neovasculization is maximal - collagen fibrils become more abundant and begin to bridge the incision - epidermis recovers to normal thickness - differentiation of surface cells yields a mature epidermal architecture with surface keratinization |
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healing by first intention events in second week. 2 events
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- continued accumulation of collagen and proliferation of fibroblasts
- leukocytic infiltrate, edema, and increased vascularity largely disappear |
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heaing by first intention events by end of first month. 4 events
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- scar comprises a cellular connective tissue devoid of inflammatory infiltrate
- covering of intact epidermis - line of incision is lost - tensile strength of would increases thereafter, but it may take months for the wounded area to obtain its maximal strength |
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healing by secondary intention differences from healing by primary intention
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1) large tissue defects initially have more fibrin and more necrotic debris and exudates that must be removed; hence, the inflammatory reaction is more intense
2) much larger amounts of granulation tissue are formed. 3) wound contraction - myofibroblasts contribute to contraction |
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growth factors and cytokines which stimulate collagen synthesis in wound healing (3, 2)
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- growth factors: PDGF, FGF, TGF-beta
- cytokines: IL-1 and IL-4 |
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cell division growth factors (4)
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EGF, PDGF, IGF, FGF
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angiogenesis growth factors
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VEGF, FGF
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matrix modification growth factors
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TGF beta, CTGF
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types of fibrosis in wound healing
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excessive accumulation of extracellular matrix
keloid: benign overgrowth beyond the wound margin hypertrophic scar: disfiguring, but within the wound margin |
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four chronic wound types
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decubitus ulcer (pressure sore)
- infarction of the skin over bony processes arterial ulcer - insufficiency of blood supply venous (stasis) ulcer - failure of valves to prevent lymphadema diabetic ulcer - complication of hyperglycemia, atherosclerosis, impaired microcirculation, and hypoproliferation |