Wound Repair Flashcards
goal of wound healing
restore the structural and functional integrity of injured tissue; depends on the extent of the injury; depends on type of tissue
outcomes of wound healing
regeneration and resolution;
repair
regeneration and resolution; tissues where it takes place
back to original structure and function;
corneal epithelium, bone, superficial skin
repair; tissues where it takes place
repair of structure, but not function;
heart, brain, retina
duration of wound healing; when does it begin?
days to years; begins during acute inflammation
primary intention wound healing
minimal tissue loss; ability to close edges back up without a gap; clean cut, not too deep; can occur internally or externally; begins with fibrin blood clot, preventing further entry of debris; epithelium is regenerating and granulation tissue develops; little to no scarring (scarring can be internal); largely restored to normal structure and function
secondary intention wound healing
significant tissue loss; can occur internally or externally; edges of wound aren’t in apposition/can’t close up; must restore integrity by filling in gap; starts with blood clot; then granulation tissue develops; edges grow back together over time; more collagen and granulation; will take longer and leave more scarring
wound healing phases
1) inflammatory
2) proliferative
3) maturation
(traditional phases that all wounds go through)
inflammatory phase
- ~day 2-5
- acute inflammation signals clotting factors and phagocytic cells
- clot blood
- destroy offending agent
- debridement: removing clots, microorganisms, erythrocytes, and dead tissue cells; prepares tissue for regrowth; phagocytosis by macrophages
- edema dissipates after debridement
proliferative phase (growth phase)
- ~day 5 to week 3
- granulation tissue (GT) develops: vascularized connective tissue full of macrophages; angioblast proliferation (blood vessel growth); fibroblast proliferation (collagen and extracellular matrix synthesis; temporary structure as precursor to the final scar)
- contraction: myofibroblasts gradually close wound
- epithelialization: epithelial cells proliferate and cover the wound; matrix metalloproteinases remodel new collagen in wound; cellular differentiation occurs when edges of wounds meet
maturation phase
- ~week 3 to year 2
- continued cellular differentiation (epithelium)
- scar remodeling, trying to make the scar smaller: collagen becomes more organized; granulation tissue becomes connective tissue
local factors that affect wound healing
- location
- size
- infection (leading cause of delayed wound healing)
- mechanical factors
- foreign bodies- affects epithelialization
systemic factors that affect wound healing
- nutrition (esp. protein & vitamin C deficiencies)
- metabolic disease (DM 2, depresses immune system)
- vascular disease (atherosclerosis, arteriosclerosis, varicose veins)
- hormones (cortisol, glucocorticoids are anti-inflammatory); systemic meds like steroids
dysfunctional wound healing
- dehiscence (mechanical): excessive strain, obesity, infection
- ulceration: inadequate blood supply, infection, mechanical factors (bed sore)
- keloid: excessive fibroblast growth
- contracture: myofibril activity
tissue repair in the eye
- responds to trauma like any other tissue: inflammation, vascularization, scar formation
- healing can affect vision: retinal injury -> glial cell proliferation -> fibrotic traction
