The document summarizes the four phases of skin injury repair: 1) Inflammatory phase where bleeding occurs and an inflammatory response is triggered. 2) Migratory phase where a scab forms and cells migrate to remove debris. 3) Proliferation phase where the scab is undermined by epidermal cell migration and fibroblast activity produces collagen. 4) Scarring phase where the scab is shed and scar tissue forms and elevates the epidermis over several weeks.

1. Unit
3
The
Integumentary
System
Chapter 5 in Textbook
3.5 Injury & Repair

2. Repair of Skin Injuries
Inflammatory Phase
• Bleeding occurs at the site of injury
immediately after the injury, and
mast cells in the region trigger on
inflammatory response.

3. Repair of Skin Injuries
Migratory Phase
• After several hours, a scab has
formed and cells of the stratum
basale are migrating along the
edges of the wound. Phagocytic
cells are removing debris, and
more of these cells are arriving
with the enhanced circulation in the
area. Clotting around the edges of
the affected area partially isolates
the region.

4. Repair of Skin Injuries
Proliferation Phase
• About a week after the injury, the
scab has been undermined by
epidermal cells migrating over the
collagen fiber meshwork produced
by fibroblast proliferation and
activity. Phagocytic activity around
the site has almost ended, and the
fibrin clot is dissolving.

5. Repair of Skin Injuries
Scarring Phase
After several weeks, the scab has
been shed, and the epidermis is
complete. A shallow depression
marks the injury site, but fibroblasts
in the dermis continue to create scar
tissue that will gradually elevate the
overlying epidermis.