Section 3 Wound healing

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Section 3 Wound healing
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• 1. Definition
• Refers to the bodys replacement of destroyed
  tissue by living tissue
• 2. Stages in healing of wound
• (1) Escape of blood and exudates
• (2) Acute inflammation

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• (3) Contraction of the wound. The causes of
  contraction are not known but possible mechanisms
  are
• ? Shrinkage of scab in superficial wounds
• ? Contraction properties of granulation tissue
  attributable to contraction of myofibroblasts or
  tissue re-modeling.

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• (4) Proliferation and migration of fibroblasts
  and endothelial cells.
• (5) Progressive increase in mature collagen
  fibres during the second week forming a scar.
• (6) Loss vascularity and shrinkage of the scar.

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• 3. Type of wound healing
• (1) Healing by fist intention
• A clean wound with a minimum of space between
  the margins.

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healing by first intention
(????? ???,1998 ?? )
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• (2) Healing by second intention
• Healing by second intention differs from
  healing by first intention in
• ? Greater tissue loss
• ? More inflammatory exudates and necrotic
  material to remove
• ? More granulation tissue therefore a bigger
  scar

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healing by second intention
(????? ???,1998 ?? )
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• ? Wound contraction necessary
• ? Slower process
• ? Increased liability to infection
• (3) Healing under scab

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• 4. Factors influencing wound healing
• (1) Local factors adversely affecting healing
• ? Type of wounding agent blunt, crushing,
  tearing etc.
• ? Infection
• ? Foreign bodies in wound
• ? Poor blood supply

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• ? Excessive movement
• ? Poor apposition of margins, e. g. large
  haematoma formation
• ? Poor wound contraction due to tissue tethering
• ? Infiltration by tumor.
• ? Previous irradiation.

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• (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

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• ? Excessive glucocorticosteroid production or
  administration
• ? Fall in temperature
• ? Jaundice

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• (3) Factors accelerating wound healing
• ? Ultraviolet light.
• ? Administration of anabolic steroids,
  deoxycorticosterone acetate, cell growth factors.
• ? Rise in temperature.