repair and regeneration Flashcards
After tissue is damaged it undergoes inflammation and then healing
what are the 2 main types of healing
regeneration
repair
define regeneration
damaged cells are replaced and return to normal.
define repair
damaged cells cannot be replaced so they undergo fibrosis and scaring.
what are the 3 types of cell population
Liable cell population
Stable cell population
Permanent cell population
what does liable cell population mean
always regenerate.
High normal turnover- to maintain integrity.
Active stem cell population
Excellent regenerative capacity
give an example of a liable cell population
epithelial cells.
what does stable cell population mean
(quiescent) cell populations can regenerate if need be. Low physiological turnover Turnover can massively increase if needed. Good regenerative capacity.
give an example of a stable cell population
liver and renal tubules.
what does permanent cell population mean
No physiological turnover
Long life cells
No regenerative capacity (nb recent stem cell research)
give an example of a permanent cell population
eg neurons, muscle cells
Why the architecture of the damaged tissue needed to be present in order for cells to proliferate and replace those which are lost
It enables cells to replace those lost in an order fashion so that the organ or tissue can retain it’s function.
Give an example of a condition where the tissue loses it architecture and cannot be replaced.
eg cirrhosis.- There is collapse of the reticulin (connective tissue) framework of the liver so that regeneration of liver cells cannot repopulate the normal architecture. This leads to the formation of regenerative nodules divided by fibrous septa.
what are the key properties of stem cells
prolonged self renewal
asymmetric replication
reservoirs present in many adult tissues.
what are the 4 main stages in self renewal and differentiation.
stem cell compartment
amplifying cell compartment
Differentiating compartment
Terminal differentiation.
what injury can cause damage to the stem cell compartment.
full thickness burns, radiation.
what are the functional consequences of repair by fibrosis of the heart post MI
Mechanical- loss of pumping capacity
Electrical-arrhythmia or might disrupt the cardiac conducting system if in a critical point (eg His bundles), giving heart block.
what factors help to control hyper proliferation.
Covering of defect
Contact inhibition
Complex control by growth factors, cell-cell and cell-matrix interactions
what are the components of newly formed granulation tissue.
New capillaries- so macrophages and neutrophils can get to the tissue.
Phagocytic cells- neutrophils (acute) and macrophages (chronic). Initially neutrophils move in and then macrophages move into tissue if need- they remove dead tissue.
Myo) fibroblasts- produce collagen, and if myo they have myelin which is used to contract the tissue
why do we have new capillaries in granulation tissue.
so macrophages and neutrophils can get to the tissue.
which cells come in first neutrophils or macrophages
neutrophils.
what is the function of myofibroblasts
Produce collagen, and if myo they have myelin which is used to contract the tissue
As granulation tissue matures 3 changes take place, these are
vascularity and cellularity decrease
Collagen and wound strength increases
what local factors inhibit the healing process
infection, haematoma, blood supply, foreign bodies, mechanical stress.
what systemic factors inhibit the healing process.
Age, drugs, anaemia, diabetes, malnutrition, catabolic states, vitamin C deficiency, trace metal deficiency.
why does a catabolic state now allow healing to take place
breaks down proteins.
what is wound healing by primary intention
Clean, uninfected surgical wound
Good haemostasis
Edges apposed eg with sutures or staples
what is wound healing by secondary intention.
Wound edges not apposed- not together
- Extensive loss of tissue
- Apposition not physically possible
- Large haematoma
- Infection
- Foreign body
which has more granulation and scarring- healing by primary or healing by secondary intention
healing by secondary intention.
what immune cell removes death tissue and scar tissue from a granulation
macrophages
Be`fore granulation what forms at the site of injury
fibroclot.
when a bone is fractured what process commonly occurs at the site of injury
Haematoma.
Is the haematoma following fracture injury organised or not
yes it is organised.
How is bone reformed at the site of feature an haematoma.
Osteoblasts (specialized cells) lay down woven bone
(=callus)
• Remodelling according to mechanical stress
Replacement by lamellar bone
what pathological process takes place in the brain following injury
Gliosis rather than scarring- due to proliferation of reactive astrocytes.
damaged tissue is often removed leaving a cyst.
Is healing a controlled process.
Yes- tightly controlled by a complex network of cytokines
why is linking healing with cancer important.
control of healing molecules are targets for cancer, as tumours must generate a new blood supply and supporting stroma (Which occurs in granulation)
supporting cell in normal tissue are collagen and fibroblast, what are the supporting cells in the brian
glial cells.
targets for cancer treatment include
VEGF- vasculognesis
EGF
PDGF
TGF-B
what often happens to tissue which undergoes healing by secondary intention
undergoes contraction.
