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  1. 1. Course = VPAT- 801 Submitted to: Dr. D. V. Joshi Professor and Head, Veterinary Pathology Department, Sardarkrushinagar Dantiwada Agricultural University, Submitted by: Chirag M. Modi Reg. no.- 04-0442-08
  2. 3. Skin: structure and function <ul><li>Largest organ of the body </li></ul><ul><li>Primary function is protective </li></ul><ul><li>Composed of several layers </li></ul><ul><ul><li>Outer Epidermis and Stratum Corneum </li></ul></ul><ul><ul><li>Dermis, containing the capillary network </li></ul></ul><ul><ul><li>Subcutaneous layer (hypodermis, adipose layer) </li></ul></ul>
  3. 4. Skin: structure and function <ul><li>Thickness varies from a thin membrane at internal flexures (e.g. elbows), to thicker at the soles of the feet which bear considerable pressures </li></ul><ul><li>Hair follicles, sebaceous glands, and sweat glands pass through the epidermis, but arise from the dermal layer </li></ul>
  4. 5. <ul><li>Wound healing: </li></ul><ul><li>Wound healing is a complex, but orderly process </li></ul><ul><li>Wound healing in the skin involves both </li></ul><ul><li>epithelial regeneration and the formation of </li></ul><ul><li>connective tissue scar. </li></ul><ul><li>Each different tissue in the body has specific </li></ul><ul><li>cells that provide some organ specificity to the </li></ul><ul><li>healing response. </li></ul>
  5. 6. The ways in which wounds heal <ul><li>Three basic classifications exist: </li></ul><ul><ul><li>Healing by primary intention </li></ul></ul><ul><ul><li>Healing by secondary Intention </li></ul></ul><ul><ul><li>Delayed primary healing </li></ul></ul>
  6. 7. Primary union ( healing by 1st intention) -Healing of a clean linear wound /surgical incision with sligth damage of tissues  space fills with clotted blood  24 hs:PMN´ mitoses of basal epithelium  dehydration at surface  scab Primary Intention
  7. 8. <ul><li>When wound edges are directly next to </li></ul><ul><li>one another </li></ul><ul><li>Little tissue loss </li></ul><ul><li>Minimal scarring occurs </li></ul><ul><li>Most surgical wounds heal by first </li></ul><ul><li>intention healing </li></ul><ul><li>Wound closure is performed with </li></ul><ul><li>sutures, staples, or adhesive at the time </li></ul><ul><li>of initial evaluation </li></ul>Primary Intention
  8. 10. Primary union(cont.) A. 1-2 days  epithelial cells grow along cut surface B. 3 days  macrophages /granulation tissue C. 5 days  space filled /granulation tissue D. 2nd wk.  accumulation of collagen, fibroblasts E. End of 1st month  connective tissue devoid of inflammation, epidermis restored F. Tensile strength increases 70-80% of unwoun ded skin in 3 months
  9. 11. means the healing of a wound where there is a more extensive of tissue that has gradually to be filled in and replaced by new connective tissue. Healing by second intention
  10. 12. <ul><li>The wound is allowed to granulate </li></ul><ul><li>Surgeon may pack the wound with a </li></ul><ul><li>gauze or use a drainage system </li></ul><ul><li>Granulation- results in a broader scar </li></ul><ul><li>Healing process can be slow due to </li></ul><ul><li>presence of drainage from infection </li></ul><ul><li>Wound care must be performed daily to </li></ul><ul><li>encourage wound debris removal to </li></ul><ul><li>allow for granulation tissue formation </li></ul>Secondary Intention
  11. 13. <ul><li>The wound is initially cleaned, debrided and observed, typically 4 or 5 days before closure. </li></ul><ul><li>The wound is purposely left open </li></ul>Tertiary Intention (Delayed primary closure)
  12. 14. Within a few weeks, the rapidly dividing epidermis completely lines the original wound site. The fibroblasts generate new connective tissue (scar tissues), which replaces the epidermis destroyed by the wound. Scar tissue persists after the healing of particularly severe wounds .
  13. 15. <ul><li>All wounds heal following a a specific </li></ul><ul><li>sequence of phases which may overlap </li></ul><ul><li>The process of wound healing depends on the type of tissue which has been damaged and the nature of tissue disruption </li></ul><ul><li>The phases are: </li></ul><ul><ul><li>Inflammatory phase </li></ul></ul><ul><ul><li>Proliferative phase </li></ul></ul><ul><ul><li>Remodelling or maturation phase </li></ul></ul>
  14. 18. Phases of wound healing sequence Coagulation Inflammation Migration/Proliferation Angiogenesis Epithelization Contraction Fibroplasia Remodeling
  15. 19. Schematic Diagram of the Phases of Wound Healing
  16. 20. <ul><li>Immediate to 2-5 days </li></ul><ul><li>B) Hemostasis </li></ul><ul><li>Vasoconstriction </li></ul><ul><li>Platelet aggregation </li></ul><ul><li>Thromboplastin makes clot </li></ul><ul><li>C) Inflammation </li></ul><ul><li>Vasodilation </li></ul><ul><li>Phagocytosis </li></ul>Inflammatory Phase
  17. 21. <ul><li>Characterized by redness, heat, pain and </li></ul><ul><li>swelling </li></ul><ul><li>Last approximately 4 to 5 days </li></ul><ul><li>Initiates the healing process by stabilizing </li></ul><ul><li>the wound through platelet activity that </li></ul><ul><li>stops bleeding & triggers the immune </li></ul><ul><li>response </li></ul>Principles of Wound Healing Inflammatory Stage
  18. 22. <ul><li>Within 24 hours of the initial injury, neutrophils, monocytes and macrophages are on the scene to control bacterial growth and remove dead tissue </li></ul><ul><li>Characteristic red color and warmth is caused by the capillary blood system increasing circulation & laying foundation for epithelial growth </li></ul>Conti….
  19. 23. <ul><li>2 days to 3 weeks </li></ul><ul><li>B) Granulation </li></ul><ul><li>Fibroblasts lay bed of collagen </li></ul><ul><li>Fills defect and produces new capillaries </li></ul><ul><li>C) Contraction </li></ul><ul><li>Wound edges pull together to reduce defect </li></ul><ul><li>D) Epithelialization </li></ul><ul><li>Crosses moist surface </li></ul><ul><li>Cell travel about 3 cm from point of origin in all directions </li></ul>Proliferative Phase
  20. 24. Principles of Wound Healing Proliferation Stage <ul><li>Begins within 24 hours of the initial injury and may continue for up to 21 days </li></ul><ul><li>It is characterized by three events: </li></ul><ul><ul><li>Epithelialization </li></ul></ul><ul><ul><li>Granulation </li></ul></ul><ul><ul><li>Collagen synthesis </li></ul></ul>
  21. 25. <ul><li>Formation of new capillaries that </li></ul><ul><li>generate and feed new tissue </li></ul><ul><li>Granulation tissue is the beefy red tissue </li></ul><ul><li>that bleeds easily </li></ul>Granulation
  22. 26. Its histologic appearance is characterized by proliferation of fibroblasts and numerous new thin-walled, delicate capillaries edema and a loose ECM containing occasional inflammatory cells.
  23. 27. Cytokines play an important role in the evolution of granulation tissue through recruitment of inflammatory leukocytes and stimulation of fibroblasts and epithelial cells.
  24. 28. <ul><li>Formation of an epithelial layer that seals </li></ul><ul><li>and protects the wound from bacteria and </li></ul><ul><li>fluid loss </li></ul><ul><li>It is essential to have a moist environment </li></ul><ul><li>to foster growth of this layer </li></ul><ul><li>It is a very fragile layer that can be easily </li></ul><ul><li>destroyed with aggressive wound irrigation </li></ul><ul><li>or cleansing of the involved area </li></ul>Epitheliazation
  25. 29. <ul><li>Creates a support matrix for the new </li></ul><ul><li>tissue that provides it with its’ strength </li></ul><ul><li>Oxygen, iron, vitamin C, zinc, </li></ul><ul><li>magnesium & protein are vital for </li></ul><ul><li>collagen synthesis </li></ul><ul><li>This stage is the actual rebuilding and </li></ul><ul><li>is influenced by the overall patient </li></ul><ul><li>condition of the wound bed </li></ul>Collagen Synthesis
  26. 30. <ul><li>3 weeks to 2 years </li></ul><ul><li>B) New collagen forms which increases </li></ul><ul><li>tensile strength to wounds </li></ul><ul><li>C) Scar tissue is only 80 percent as </li></ul><ul><li>strong as original tissue </li></ul>Remodeling Phase
  27. 31. <ul><li>Final stage of wound healing </li></ul><ul><li>Begins around day 21 and may </li></ul><ul><li>continue for up to 2 years </li></ul><ul><li>Collagen synthesis continues with </li></ul><ul><li>eventual closure of the wound and </li></ul><ul><li>increase in tensile strength </li></ul><ul><li>Tensile strength reaches only about </li></ul><ul><li>80% of pre-injury strength </li></ul>Principles of Wound Healing Remodelling or Maturation
  28. 32. Factor affecting wound healing Systemic factor Nutrition Vitamin-C Zinc Age Glucocorticoids Local factor Ischemia Foreign body Mechanical factor
  29. 33. Pathological Aspects of wound repair <ul><li>Complications in wound healing can occur from abnormalities in any of the basis repair processes. </li></ul><ul><li>These reduce the quality of repair. </li></ul><ul><li>These factors can be placed in to three groups </li></ul><ul><li>Inadequate formation of granulation tissue </li></ul><ul><li>Excessive formation of granulation tissue </li></ul><ul><li>Contraction </li></ul>
  30. 34. <ul><li>Inadequate formation of granulation tissue </li></ul><ul><li>Wound dehiscence </li></ul><ul><li>Ulceration </li></ul><ul><li>Excessive formation of granulation tissue </li></ul><ul><li>Proud flesh </li></ul><ul><li>Keloid </li></ul><ul><li>Contraction </li></ul><ul><li>Contracture </li></ul>Conti…
  31. 35. - CNS  gliosis ( may cause hydrocephalia) -PNS  neurons can regenerate their axons in ideal conditions, but lack of alignment or inflammation  traumatic “neuroma” (Schwann cells+fibroblasts ) -Lungs  interstitial pulmonary fibrosis or peribronchial fibrosis  bronchectasis -Pleura  pleural fibrosis/adhesions(TB ) HEALING IN SPECIFIC TISSUES
  32. 36. -Stomach  fibrous stenosis of pylorus (gastric ulcer) -Rectosigmoid  fibrous stenosis due to ven. diseases -Liver  cirrhosis -Fallopian tubes  fibrous occlusion due to P.I.D. -Skin  contracture / deformation(burns) HEALING IN SPECIFIC TISSUES(cont)
  33. 37. -Myocardium  fibrosis  ventricular aneu- rysm -Endocardium  valvular fibrosis +deformat. -Pericardium  constrictive pericarditis,peri cardial adhesions -Peritoneum  adhesions and fibrous bands -Esophagus  fibrous stricture(due to burns) HEALING IN SPECIFIC TISSUES(cont)
  34. 38. Clinical appearance of wound <ul><ul><li>Slough (yellow) </li></ul></ul><ul><ul><li>Necrotic tissue (black) </li></ul></ul><ul><ul><li>Infected tissue (green) </li></ul></ul><ul><ul><li>Granulating tissue (red) </li></ul></ul><ul><ul><li>Epithelialising (pink) </li></ul></ul>
  35. 39. Sloughy wound
  36. 40. Necrotic wound
  37. 41. Granulating wound
  38. 42. Infected wound
  39. 43. Epithelialising wound
  40. 44. Thank you