repair and regeneration

Question 1

After tissue is damaged it undergoes inflammation and then healing
what are the 2 main types of healing

Answer 1

regeneration

repair

Question 2

define regeneration

Answer 2

damaged cells are replaced and return to normal.

Question 3

define repair

Answer 3

damaged cells cannot be replaced so they undergo fibrosis and scaring.

Question 4

what are the 3 types of cell population

Answer 4

Liable cell population
Stable cell population
Permanent cell population

Question 5

what does liable cell population mean

Answer 5

always regenerate.
High normal turnover- to maintain integrity.
Active stem cell population
Excellent regenerative capacity

Question 6

give an example of a liable cell population

Answer 6

epithelial cells.

Question 7

what does stable cell population mean

Answer 7

(quiescent) cell populations
can regenerate if need be.
Low physiological turnover
Turnover can massively increase if needed.
Good regenerative capacity.

Question 8

give an example of a stable cell population

Answer 8

liver and renal tubules.

Question 9

what does permanent cell population mean

Answer 9

No physiological turnover
Long life cells
No regenerative capacity (nb recent stem cell research)

Question 10

give an example of a permanent cell population

Answer 10

eg neurons, muscle cells

Question 11

Why the architecture of the damaged tissue needed to be present in order for cells to proliferate and replace those which are lost

Answer 11

It enables cells to replace those lost in an order fashion so that the organ or tissue can retain it’s function.

Question 12

Give an example of a condition where the tissue loses it architecture and cannot be replaced.

Answer 12

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.

Question 13

what are the key properties of stem cells

Answer 13

prolonged self renewal
asymmetric replication
reservoirs present in many adult tissues.

Question 14

what are the 4 main stages in self renewal and differentiation.

Answer 14

stem cell compartment
amplifying cell compartment
Differentiating compartment
Terminal differentiation.

Question 15

what injury can cause damage to the stem cell compartment.

Answer 15

full thickness burns, radiation.

Question 16

what are the functional consequences of repair by fibrosis of the heart post MI

Answer 16

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.

Question 17

what factors help to control hyper proliferation.

Answer 17

Covering of defect
Contact inhibition
Complex control by growth factors, cell-cell and cell-matrix interactions

Question 18

what are the components of newly formed granulation tissue.

Answer 18

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

Question 19

why do we have new capillaries in granulation tissue.

Answer 19

so macrophages and neutrophils can get to the tissue.

Question 20

which cells come in first neutrophils or macrophages

Answer 20

neutrophils.

Question 21

what is the function of myofibroblasts

Answer 21

Produce collagen, and if myo they have myelin which is used to contract the tissue

Question 22

As granulation tissue matures 3 changes take place, these are

Answer 22

vascularity and cellularity decrease

Collagen and wound strength increases

Question 23

what local factors inhibit the healing process

Answer 23

infection, haematoma, blood supply, foreign bodies, mechanical stress.

Question 24

what systemic factors inhibit the healing process.

Answer 24

Age, drugs, anaemia, diabetes, malnutrition, catabolic states, vitamin C deficiency, trace metal deficiency.

Question 25

why does a catabolic state now allow healing to take place

Answer 25

breaks down proteins.

Question 26

what is wound healing by primary intention

Answer 26

Clean, uninfected surgical wound
Good haemostasis
Edges apposed eg with sutures or staples

Question 27

what is wound healing by secondary intention.

Answer 27

Wound edges not apposed- not together

1. Extensive loss of tissue
2. Apposition not physically possible
3. Large haematoma
4. Infection
5. Foreign body

Question 28

which has more granulation and scarring- healing by primary or healing by secondary intention

Answer 28

healing by secondary intention.

Question 29

what immune cell removes death tissue and scar tissue from a granulation

Answer 29

macrophages

Question 30

Be`fore granulation what forms at the site of injury

Answer 30

fibroclot.

Question 31

when a bone is fractured what process commonly occurs at the site of injury

Answer 31

Haematoma.

Question 32

Is the haematoma following fracture injury organised or not

Answer 32

yes it is organised.

Question 33

How is bone reformed at the site of feature an haematoma.

Answer 33

Osteoblasts (specialized cells) lay down woven bone
(=callus)
• Remodelling according to mechanical stress
Replacement by lamellar bone

Question 34

what pathological process takes place in the brain following injury

Answer 34

Gliosis rather than scarring- due to proliferation of reactive astrocytes.
damaged tissue is often removed leaving a cyst.

Question 35

Is healing a controlled process.

Answer 35

Yes- tightly controlled by a complex network of cytokines

Question 36

why is linking healing with cancer important.

Answer 36

control of healing molecules are targets for cancer, as tumours must generate a new blood supply and supporting stroma (Which occurs in granulation)

Question 37

supporting cell in normal tissue are collagen and fibroblast, what are the supporting cells in the brian

Answer 37

glial cells.

Question 38

targets for cancer treatment include

Answer 38

VEGF- vasculognesis
EGF
PDGF
TGF-B

Question 39

what often happens to tissue which undergoes healing by secondary intention

Answer 39

undergoes contraction.