34 Healing (Primary and Secondary Intention Healing) Flashcards
What is the difference between primary and secondary intention healing?
Primary intention healing: when minimal damage occurs, and full healing is possible
Secondary intention healing: when extensive damage occurs and full healing is not possible, scar tissue will be formed
what are the two stages of primary intention healing?
1: preparative phase: up to 36 hours
2: reparative phase: after 36 hours
what happens in the preparative phase of primary intention healing?
occurs in the first 36 hours
bleeding sealed off by a blood clot (cross linked mesh of platelets and fibrin)
wound seals together, creating a barrier to bacterial invasion
cellular debris cleared by neutrophils and macrophages
what happens in the reparative phase of primary intention healing?
beyond the first 36 hours
basal cells divide and create new cells, pushing upward towards apical layer
fibroblasts migrate to area and produce collagen
fibrin mesh acts as a scaffold for fibroblasts and collagen deposits
granulation tissue grows into the wound from surrounding healthy tissue
epithelial cells grow into the wound and divide into various epidermal layers
what happens in the reconstructive stage of secondary intention healing?
bleeding sealed off by a blood clot containing a cross linked mesh of fibrin and platelets
fibrin mesh acts as a scaffold for fibroblasts and collagen deposits
granulation tissue grows into the wound from surrounding healthy tissue, and fibroblasts form scar tissue
scar is formed
what are the two major stages of secondary healing?
- reconstructive
2. maturation
what happens in the maturation phase of secondary intention healing?
scar remodelling and contraction
within 2-3 weeks after maturation has begun, the scar tissue has gained two thirds of its eventual strength (at best will be only 80% as strong as original tissue)
