8 - Repair and regeneration Flashcards
Difference between regeneration and repair
Regen = tissues return to normal Repair = dmged cells cannot be replaced by like cells - hence fibrosis and scarring; loses specialised function
What is a labile cell population?
High normal turnover
Active stem cell population
Excellent regen capacity
e.g. epithelia
Stable cell population
Low physiological turnover
Turnover can massively increase if needed
Good regen capacity
e.g. liver, renal tubules
Permanent cell population
No physiological turnover
Long life cells
No regen capacity - as so specialised
e.g. neurons, muscle cells
why can a cirrhotic liver not repopulate its normal cells?
Long term damage causes collapse of reticulin (connective tissue framework). Leeds to formation of regen nodules divided by fibrous septa.
Compartments for stem cells
A stem cell can be stored in a stem cell compartment of progress through:
Amplifying cell compartment -> differentiating compartment -> terminal differentiation
What can destroy stem cells
Full thickness burn + radiation
What is granulation tissue?
Tissue with new capillary loops + phagocytic cells + (myo)fibroblasts
Skin wound healing in general
First by: primary intention
Second: secondary intention
What is healing by first intention?
Clean, uninfected surgical wound with good haemostasis
The edges are apposed with sutures or staples.
Gets small fibrous union
What is healing by second intention?
Wound edges not apposed
Not a fundamentally different process
More florid granulation tissue rxn
More extensive scarring
Why would wound edges not apposed?
Extensive loss of tissue Apposition not physically possible Large haematoma Infection Foreign body
When would you take sutures out?
Roughly 7 days after
How do fractures heal?
Haematoma is organised
Removal of necrotic fragments
Osteoblasts lay down woven bone (=callus)
Remodelling according to mechanical stress
Lamellar bones replace woven
What does non-union of a fracture look like?
Misalignment
Movement
Infection
Interposed soft tissue
