Healing & Repair Flashcards
AUCOM
_______indicates replacement of dead (damaged) tissue by healthy tissue derived from parenchymal or connective tissue element
Healing (repair)
Healing comprises:
Regeneration
Connective tissue response
replacement by surviving specialized parenchymal cells.
Regeneration
replacement of damaged tissue by granulation tissue & its subsequent maturation into fibrous tissue (scar formation)
Connective tissue response
replacement of damaged tissue by granulation tissue & its subsequent maturation into fibrous tissue
scar formation)
Relative contribution of regeneration and connective tissue response vary according to:
1.Type of tissue involved by damage
2.Nature
3. severity
4. duration
The cell cycle consists of:
- Presynthetic growth phase (G1) 2. DNA-synthetic phase (S)
- Premitoticgrowth phase 2 (G2)
- Mitotic phase (M)
*Quiescent cells are in a physiologic state(G0).
Presynthetic growth phase
G1
Premitotic growth phase 2
G2
the phase in G1 at which the cell gets committed to the cell cycle without further need of the growth factor that initiated cell division.
Restriction point
prevent DNA replication or mitosis of damage cells and either transiently stop the cell cycle to allow for DNA repair or eliminate irreversibly damage cells by apoptosis
Checkpoint controls
Entry & progression through cell cycle controlled by changes in levels/activities of _________
Cyclins
Levels of various cyclins
- increase at specific stages of cell cycle followed by
- rapid degradation as cell moves through the cycle.
Cyclins accomplish regulatory functions by_______
complexing with then activating CDKs ( cyclin dependent kinases ).
Cyclins/CDKs complexes exert effects by ______
phosphorylating selected group of protein substrates
where in the cell cycle are: labile cells
continually cycling
where in the cell cycle are: stable cells
G0 (until they need to proliferate /injury/)
where in the cell cycle are: permanent cells
do not enter cell cycle
Cells of body divided into three groups depending on relationship to cell cycle.
- Labile cells
- Stable cells
- Permanent cells
Ability of proliferation inversely correlated with
degree of differentiation
Under normal conditions are continuously dividing & dying cells
Labile cells
Labile cells examples
Haemopoietic cells
Surface epithelial cells
Component of ECM
- fibrous structure proteins include collagens & elastin’s.
- water –hydrated gels ( proteoglycans and hyaluronan. permit lubrication
3.Adhesive glycoproteins connect the matrix elements.
