classify and compare different types of healing

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Healing occurs by

Primary Intension - occurs in a clean cut scar, well apposed my a stich, where no pus, debris or gaping is present. Heals with less granulation and without scar.

Secondary Intention - occurs in Dirty wound, gaping with loss of tissue, wound with infection or Foreign body. Here there is more inflammatory response with more granulation tissue, scar contraction occurs and heals with scar. If severe may require intervention.
answered May 29, 2012 by Angrybird Sresta Medical student (607 points)
selected Jun 4, 2012 by Sulabh Shrestha

First intention healing

  1. This takes place where there is close apposition of clean wound edges.
  2. Thrombosis in cut blood vessels prevents haematoma formation.
  3. Coagulated blood forms a surface scab that keeps the wound clean.
  4. Fibrin precipitates to form a weak framework between the two edges.
  5. Capillaries proliferate to bridge the gap.
  6. Fibroblasts secrete collagen into the fibrin network.
  7. Basal epidermal cells bridge the gap and are eventually resorbed.
  8. The elastic network in the dermis cannot be replaced.

Second intention healing

  1. This takes place in wounds where skin edges cannot be cleanly apposed.
  2. There is phagocytosis to remove debris.
  3. Granulation tissue to fill in defects.
  4. Epithelial regeneration covers the surface.
answered Jul 2, 2012 by Mike Junior Resident (2,007 points)
commented Jul 2, 2012 by Mike Junior Resident (2,007 points)
Also the four stages of wound healing are:

1. Haemostasis: immediate. In response to exposed collagen, platelets aggregate at the wound and degranulate, releasing inflammatory mediators. Clotting and complement cascades activated. Thrombus formation and reactive vasospasm achieve haemostasis

2. Inflammation: 0-3 days. Vasodilatation and increased capillary permeability allow inflammatory cells to enter wound, and cause swelling. Neutrophils amplify inflammatory response by release of cytokines; reduce infection by bacterial killing; and debride damaged tissue. Macrophages follow and secrete cytokines, growth factors, and collagenases. They phagocytose bacteria and dead tissue and orchestrate fibroblast migration, proliferation, and collagen production

3. Proliferation: 3 days-3 weeks. Fibroblasts migrate into the wound and synthesize collagen. Specialized myofibroblasts containing actin cause wound contraction. Angiogenesis is stimulated by hypoxia and cytokines and granulation tissue forms

4. Remodelling: 3 weeks-1 year. Re-orientation and maturation of collagen fibres increases wound strength.

Third degree or Tertiary Intention of wound healing:

  • The wound is initially cleaned, debrided and observed, typically 4 or
  • 5 days before closure. The wound is purposely left open
  • Examples: healing of wounds by use of tissue grafts.

It is done in case of contaminated, dirty wounds.

answered Jul 6, 2012 by Sulabh Shrestha Doctor of Medicine (5,553 points)