Wound Healing and Repair Flashcards
Regeneration vs Healing
Regeneration is complete restitution of lost tissues. Healing may restore original structures, but involves collagen deposition and scar formation.
Early stages of healing involve:
0-3 Days. Fibrin clot formed, inflammation and phagocytosis, and re-epithelialization to reseal the lost barrier.
Middle stages of healing involve:
1-10 days. Formation of granulation tissue, formation of type III collagen matrix and wound contraction.
Late stages of healing involve:
Cross linking and remodeling. Type 1 collagen predominates
Organization
Secondary changes in the thrombus, dissolution of the clot, formation of new vessels, deposition of stroma. Used to describe a wound that is undergoing repair.
Granulation tissue
A hallmark of middle stages of healing. Macrophages, myofibroblasts, and fibroblasts. Lots of angiogenesis.
PDGF and FGF
Induces fibroblast, connective tissue and smooth muscle growth.
Fibrogenic cytokines, angiogenic cytokine, epithelial proliferation cytokine
TGF B and IL-4, VEGF, EGF
Myofibroblast
Has features of a fibroblast and a smooth muscle cell. Instrumental in wound repair because it contracts the wound.
Histology: Early scar vs late scar
Early scar has a lot of granulation tissue, many capillaries and an edematous stroma. Late scar has more regular collagen, and lots of fibrosis.
Are elastic fibers replaced in scar tissue?
No
Maximum tensile strength of a wound?
70%, reaches this at about 3 months.
What is the source of reepithelalization? Its purpose?
Hair follicle contain stem cells in bulge and sebaceous glands. To reform protective barrier.
Two mechanisms of reepithelialization
Leap frogging and train method.
Labile Vs Stable Cells
Labile is rapidly dividing, usually epithelial cells. Stable cells don’t divide much unless there is a stimulus (liver).
