Regeneration And Repair Flashcards
What is regeneration?
What is repair?
Regeneration - Complete restoration of tissue architecture and fx (good as new)
Repair - Restoration of fx, BUT altered architecture (scars)
What are the 4 phases of tissue repair?
Hemostasis - Clot formation
Inflammatory - Infiltration of immune cells and initiation of repair
Reparative (Proliferative) phase - Migration of cells and formation of granulation tissue
Wound contraction and scarring (not always though)
What is hemostasis?
Liquid blood to fibrillar gel
Primary goal - STOP the bleeding
Secondary goal - INITIATE healing
_________ of platelets leads to coagulation cascade.
Disruption
*Clot unites edges of wound, and FIBRIN provides a scaffold for future cell migration
T/F - Clot is different in the oral cavity. It is softer and more easily detached.
TRUE
What is Von Willebrand disease?
Lack of the Von Willebrand Factor
-This factor causes platelet aggregation by interacting with platelet surface proteins
—*THIS IS PROMINENT IN PRIMARY HEMOSTASIS
What is primary hemostasis?
Vascular spasm (constriction) and initial platelet plug in a damaged blood vessel
Platelets bind collagen directly via what 2 things?
GPVI
-Glycoprotein VI
Alpha2beta1 integrin
When does secondary hemostasis occur?
Simultaneously with primary hemostasis or just after primary
Secondary hemostasis has two pathways.
Extrinsic
Intrinsic
Tell me about extrinsic.
Factor VII and tissue factor interactions and that initiates the cascade
- Called extrinsic b/c it req’s tissue factor which is normally NOT found in blood
Tell me about intrinsic.
Initiated by damaged endothelium (due to collagen exposure)
- Called intrinsic b/c it involves factors found in the blood, not tissue factor
What is the main point of both pathways?
Conversion of prothrombin into thrombin, which converts soluble fibrinogen into insoluble fibrin
*Ca2+ is req’d at many steps
**Fibrin cross-links and forms a mesh, trapping RBCs and WBCs, resulting in a blood clot
What WBCs are first on the scene?
PMNs
What WBCs are second to arrive?
Macrophages
-Clear damaged tissue and foreign material
What are the main leukocytes involved?
T cells in particular
What happens in the reparative/proliferative phase?
Mobilization of adj cells (epithelium)
Cells migrate under fibrin clot - forming a “granulation tissue”
Collagen type IV is found where?
BASAL LAMINA
When epithelial cells migrate, what do they form?
New basal lamina
*Also redistribution of integrin receptors and formation of new hemidesmosomes
Then, fibroblast recruitment occurs, and proliferation of fibroblasts in the wound. Collagen fills the defect, forms a scaffold
What is angiogenesis?
Regeneration of blood vessels
*TGFbeta, VEGF, FGF-2 are factors important in healing the wound and blood vessels
What cells do wound contraction?
Myofibroblasts
What do myofibroblasts do?
Align around wound, form cell junctions, and attach to connective tissue fibrin around wound (like a purse string)
Wound is drawn together
Oral mucosa is typically not scarred. Why?
No one really knows
If the source of inflammation is removed in periodontal disease, the formation of what stimulates reattachment of connective tissues?
Fibrin clot
