Module 5

• What does the body attempt to heal early in the process of inflammation?

  Damage induced by local injury
• How are inflammation and repair related?

  They are closely intertwined processes
• What are the two distinct processes the body uses for repair?

  1. Regeneration: Replacement with same type cells
  2. Replacement by connective tissue
• Why is regeneration advantageous for repairs?

  It restores the organ to normal functioning
• What factors govern the extent of repair by regeneration?

  Regenerative capacity of cells and injury severity
• How are cells categorized based on their regenerative capabilities?

  1. Labile cells: Proliferate throughout life
  2. Stable cells: Low replication, can be stimulated
  3. Permanent cells: Do not replicate significantly
• What type of cells are stable cells?

  Cells that replicate at low levels
• Which cells are classified as permanent cells?

  Nerve cells, skeletal muscle cells, cardiac muscle cells
• How are injuries in organs with permanent cells typically repaired?

  By connective tissue replacement
• What influences whether repair occurs by regeneration or connective tissue replacement?

  The extent of the injury
• What role do stroma and basement membranes play in repair?

  They provide scaffolding critical for regeneration
• When does repair by connective tissue replacement predominate?

  • When injuries occur in permanent cell tissues
  • When extensive damage to stromal framework occurs
• What is granulation tissue?

  A specialized tissue formed during healing
• When does granulation tissue typically appear after injury?

  Three to five days
• What cells primarily compose granulation tissue?

  Proliferating fibroblasts and blood vessels
• What is angiogenesis?

  The process of forming new blood vessels
• What are the four basic steps of angiogenesis?

  1. Enzymatic degradation of basement membrane
  2. Migration of endothelial cells
  3. Proliferation of endothelial cells
  4. Maturation and organization into capillary tubes
• Why does granulation tissue tend to be edematous?

  Due to leaky inter-endothelial junctions
• What characteristics do fibroblasts in granulation tissue develop?

  Similarities with smooth muscle cells
• What are myofibroblasts?

  Fibroblasts with smooth muscle cell similarities
• What is the role of macrophages in granulation tissue?

  To eliminate injuring agents and debris
• What is "blanching" of the wound?

  The removal of excess granulation tissue
• What types of cells may be present in granulation tissue?

  Macrophages, neutrophils, lymphocytes, eosinophils
• What is first intention healing also known as?

  Primary union
• When does first intention healing occur?

  When there is no contamination and edges are approximated
• What fills the incision space after suturing?

  Blood containing fibrin and blood cells
• What forms on the surface of the clot?

  A scab
• What type of cells appear at the edges of the incision within 24 hours?

  Neutrophils
• What begins to proliferate at the edges of the incision?

  The epithelium
• What do epithelial cells form under the scab?

  A thin continuous epithelial layer
• What happens by 72 hours after the incision?

  Macrophages are the most numerous inflammatory cells
• What starts to develop by 72 hours?

  Granulation tissue
• What is present but does not bridge the incision site by 72 hours?

  Collagen fibers
• What happens to the epidermis by day 5?

  It returns to its normal thickness
• What begins to bridge the incision by day 5?

  Collagen fibers
• What occurs during the second week of healing?

  Accumulation of collagen fibers and fibroblast proliferation
• What disappears during the second week of healing?

  Inflammatory cells and edema
• What does blanching refer to?

  Collagen accumulation and regression of vascular channels
• What is present at the end of one month of healing?

  A connective tissue scar
• What is the condition of the connective tissue scar after one month?

  Devoid of inflammatory cells