Lecture 12 2/22/24 Flashcards
What are the options for healing responses in the tissues?
-return to normal structure/function
-healing by replacement fibrosis
-healing by sequestration (abscess/granuloma)
What are the characteristics of healing by regeneration?
-supporting connective tissue/basement membrane is intact
-tissue has capacity to regenerate
How long does healing by regeneration take?
3-5 days, then tissue returns to “normal”
What are the characteristics of healing by repair?
-supporting connective tissue/basement membrane is lost OR
-tissue not capable of proliferating
-triggers more complicated wound healing involving granulation tissue and scarring
What are the steps in wound healing?
-hemostasis
-acute inflammation
-proliferation
-remodeling
What are the general steps of hemostasis?
-vasospasm
-platelet aggregation
-platelet plug formation
-blood vessel healing
What happens during the acute inflammation stage of wound healing?
-phagocytosis of dead cells and bacteria
-breakdown of extracellular matrix due to sloppy phagocytosis
Which two components are replaced during the proliferation stage of wound healing?
-epithelial component
-stromal component
What are the characteristics of epithelial proliferation?
-similar to healing by regeneration
-must re-establish basement membrane
What is granulation tissue?
connective tissue + blood vessels
Which growth factor triggers connective tissue/fibrosis development during stromal proliferation?
TGF-B
Which growth factor triggers angiogenesis during stromal proliferation?
VEGF
What are the characteristics of granulation tissue?
-no overlying epithelium
-often has surface neutrophils
-neovascularization and fibroblasts
How does granulomatous inflammation differ from granulation tissue?
granulomatous inflammation: form of chronic inflammation w/ epithelioid macrophages/multi-nucleated giant cells
granulation tissue: form of tissue repair involving capillaries and fibroblasts
What causes wound contraction?
myofibroblasts
What happens when granulation tissue is replaced with mature fibrous connective tissue?
-decrease in:
–inflammation
–fibroblasts
–blood vessels
-collagen stays but loses cellular component
What are the characteristics of mature fibrous connective tissue/scars?
-well-organized
-avascular
-depressed
-pale
How does primary vs secondary intention wound healing differ?
-primary intention is very quick healing and less severe
-secondary intention is more severe, with more granulomatous healing
How does fibrin/fibrinous inflammation differ from fibrosis/fibrous tissue?
-fibrin/fibrinous inflammation: formed from fibrinogen, forms soft adhesions, component of acute inflammation
-fibrosis/fibrous tissue: collagen produced by fibroblasts, forms tough adhesions, common end stage of chronic inflammation
Why does fibrosis appear indented or pitted?
-loss of tissue
-contraction
