1、Section 3 Wound healing,1. Definition:Refers to the bodys replacement of destroyed tissue by living tissue2. Stages in healing of wound(1) Escape of blood and exudates (2) Acute inflammation,(3) Contraction of the wound. The causes of contraction are not known but possible mechanisms are: Shrinkage
2、of scab in superficial wounds Contraction properties of granulation tissue attributable to contraction of myofibroblasts or tissue re-modeling.,(4) Proliferation and migration of fibroblasts and endothelial cells.(5) Progressive increase in mature collagen fibres during the second week forming a sca
3、r.(6) Loss vascularity and shrinkage of the scar.,3. Type of wound healing(1) Healing by fist intentionA clean wound with a minimum of space between the margins.,healing by first intention,(参照武忠弼 病理学，1998 修改 ),(2) Healing by second intentionHealing by second intention differs from healing by first i
4、ntention in: Greater tissue loss More inflammatory exudates and necrotic material to remove More granulation tissue therefore a bigger scar,healing by second intention,(参照武忠弼 病理学，1998 修改 ), Wound contraction necessary Slower process Increased liability to infection(3) Healing under scab,4. Factors i
5、nfluencing wound healing(1) Local factors adversely affecting healing Type of wounding agent; blunt, crushing, tearing etc. Infection Foreign bodies in wound Poor blood supply, Excessive movement Poor apposition of margins, e. g. large haematoma formation Poor wound contraction due to tissue tetheri
6、ng Infiltration by tumor. Previous irradiation.,(2) General factors adversely affecting healing Age Poor nutrition Deficiency of protein Lack of Vitamin C results in abnormal granulation tissue and deficient collagen production Zinc deficiency, Excessive glucocorticosteroid production or administration Fall in temperature Jaundice,(3) Factors accelerating wound healing Ultraviolet light. Administration of anabolic steroids, deoxycorticosterone acetate, cell growth factors. Rise in temperature.,
