wound healing and repair Flashcards
What happens after tissue injury
replacement of damaged components > regenration > restoration of normal function
CT replaces damaged components > repair by connective tissue > scar formation > either normal function of fibrosis
Regeneration can only occur how
tissues composed of cells with proliferative capacity
Underlying structure of the tissue has not been too severley damaged
Repair by scar formation can occur how
Toissue composed of cells with limited or no proliferative capacity OR underlying structure of tissue is lost
The cell cycle is regulated by what?
cyclins
What is the G0 phase?
Inactive cells, unfavourable condiitons, terminally differentiated cell
Labile cells are?
Cells that constantly divide. lost and replaced, do not enter G0 phase
Stable tissues are?
Quiescent
Enter G0
Re enter cell cycle if stimulated by loss of cells, limited capacity to regenerate
Permanent tissues are?
Terminally differentiated, enter G0, cannot reenter the cell cycle. Limited stem cell replication (not sufficient for regeneration). Neurons, cardiac muscle cells
Angiogensis is
new blood vessels
what are the 3 triggers of cell proliferation
Growth factors, hormones, cytokines
organs are made of what cells and what is the stroma?
parenchyma cells
Stroma is the supporting CT including theECM
ECM
1) What proteins?
2) what are these proteins made of?
3) what type of gel is in the ECM
4) what molecules that initiate signalling and stuff?
1) fibrous structural proteins and adhesive glycoproteins
2) collagen and elastin for tensile strength
3) water hydrated gels known as proteoglycans. Compressive resistance and lubrication
4) cell adhesion molecules that initiate signalingcascades affecting locomostion, proliferation and differentiation
What are the forms of ECM?
Basement membrane and interstitial matrix
what is in the basememnt membrane?
Collagen, laminin and proteglycan
what is in the interstitial matrix
Fibrillar collagens
elastin
proteoglycan and gyaluronan
Stable cells are
1) located where?
2) limited capacity for what?
3) what organs?
1) parenchymal organs such as lunk kidney
2) limited capcity for regen
3) pancreas, adrenal, thyroid and lung
main difference between regeneration and scarring?
Regeneration wil have an intact matrix whilst scarring will have a disrupted matrix.
How does repair by connective tissue take place?
coagulative necrosis following M1
Difference between granulation tissue and scar?
Granulation tissue
- proliferating fibroblasts
- Loose ecm
- new capillaries
Scar
- Accumulation of connective tissue
Tissue repair by connective tissue involves what 4 steps
Formation of new blood vessels
Migration/proliferation of fibroblasts
Deposition of ECM (scarring)
Maturation and reorganisation of the fibrous tissue (Remodelling)
Macrophages produce wha
growth factors andcytokines that stimulate repair
M1 classical actvation
- activated by what?
- results inwhat
- activated by microbial products and IFN-Y
- Results in inflammation and microbicidial actions such as phagocytosis
M2 alternative activation
- activated by what?
- Results in what?
- activated by IL13 and IL4
- results in tissue repair, anti inflamm effects
Angiogensis known as what?
- how does it happen
- what does it provide?
Neovascularisation
- capillary sprouts from existing blood vessels
- provide collateral circulation at the site of injury
What is edema
new leaky bloody vessels
Recruitement and proliferation of fibrolasts occur when and how?
stimulated by growth factors and macrophages.
Repair begin when macrophages predominate at the site of injury following acute inflammation
Scar formation
Granulation tissue leads to what and what is the change that occurs?
scarring
changes in the composition of the ECM. Balance between collagen synthesis and degradation.
What is critical to the strength of the wound
Collagen synthesis, initial collagen type 3 is replaced by type 1.
