Session 4

Question 1

What is fibrous repair?

Answer 1

The replacement of functional tissue by scar tissue

Question 2

What are the key components of fibrous repair?

Answer 2

Cell migration
Angiogenesis
Remodelling

Question 3

What is angiogenesis?

Answer 3

The formation of new blood vessels from preexisting ones

Question 4

What cells are involved in cell migration?

Answer 4

Inflammatory
Endothelial
Fibroblasts/Myofibroblasts

Question 5

Give an example of a growth factor which increases angiogenesis.

Answer 5

VEGF

Question 6

How does the extracellular matrix aid repair?

Answer 6

Supports cells
Allows cell communication
Separates tissue compartments

Question 7

What are the three main stages in fibrous repair?

Answer 7

Inflammatory cells infiltrate - forms blood clot
Clot replaced by granulation tissue
Maturation

Question 8

What makes Granulation tissue?

Answer 8

Capillary loops and myofibroblasts

Question 9

What happens during maturation of fibrous repair?

Answer 9

The cell population falls and collagen increases matures and remodels.
Myofibroblasts contract to reduce the volume of the defect.
Vessels differentiagte and a fibrous scar remains

Question 10

What recruits inflammatory cells for fibrous repair?

Answer 10

Chemotaxis

Question 11

What causes angiogenesis in fibrous repair?

Answer 11

Angiogenic cytokines

Question 12

What causes fibrosis during fibrous repair?

Answer 12

Macrophages releasing cytokines that cause fibroblast proliferation

Question 13

What is regeneration?

Answer 13

Replacement of dead or damaged cells by functional differentiated cells. (Derived from stem cells)

Question 14

What are stem cells?

Answer 14

Cells that have limitless proliferation.

Question 15

What are Unipotent cells?

Answer 15

Can produce one type of differentiated cell eg epithelia

Question 16

What are Multipotent cells?

Answer 16

Can produce several types of differentiated cells eg haemopoietic

Question 17

What are Totipotent cells?

Answer 17

Can produce any type of cell eg Embryonic stem cells

Question 18

Give an example of Labile cells.

Answer 18

Epithelia

Haematopoietic cell

Question 19

What is the normal state of division for Labile cells?

Answer 19

Active; G1 - M - G1

Rapid proliferation

Question 20

Give an example of Stable cells.

Answer 20

Hepatocytes
Osteoblasts
Fibroblasts

Question 21

What is the normal state of division for Stable cells?

Answer 21

Resting state G0

Speed of regeneration variable

Question 22

Give an example of a permanent cell.

Answer 22

Neurone

Cardiac myocyte

Question 23

What is the normal state of division for permanent cells?

Answer 23

Unable to divide G0

Unable to regenration

Question 24

What factors can control regeneration?

Answer 24

Growth factors

Contact between basement membrane and adjacent cells

Question 25

How do growth factors encourage regeneration?

Answer 25

They promote proliferation of the stem cell population | Promote expression of gene controlling cell cycle

Question 26

What hormones can act as growth factors?

Answer 26

Oestrogen Testosterone Growth hormone

Question 27

What proteins can act as growth factors?

Answer 27

PDGF | EGF

Question 28

How can contact between basement membranes and adjacent cells control regeneration?

Answer 28

There is signalling through adhesion molecues, contact inhibition. Loss of contact = proliferation

Question 29

What is healing by Primary Intention?

Answer 29

Where there is an incised wound that has apposed edges. There is minimal clot/granulation tissue. The epidermis regenerates, Dermis undergoes fibrous repair.

Question 30

What is the risk with healing by Primary Intention?

Answer 30

If an infection becomes trapped there may be an Abscess.

Question 31

When does healing by Secondary Intention occur?

Answer 31

After an Infarct, Ulcer, Abscess or any large wound.

Question 32

What are the features of healing by Secondary Intention?

Answer 32

Unapposed wound edges Large clot Lots of Granulation tissue Epidermis regenerates from the base up

Question 33

What are the differences with healing by Secondary Intention compared to healing with Primary Intention?

Answer 33

There is more contraction There is a larger scar It takes longer It is NOT necessarily weaker

Question 34

What local factors can effect healing and repair?

Answer 34

``` Type, size and location of wound Apposition, lack of movement Blood supply Infection Foreign materials Radiation ```

Question 35

What general factors can effect healing and repair?

Answer 35

``` Age Drugs/Hormones Dietary deficiencies, especially vitamin C and Amino Acids State of health eg Chronic diseases General cardivascular status ```

Question 36

What is the type of repair in cardiac muscle?

Answer 36

Fibrosis

Question 37

What is the type of repair in Bone?

Answer 37

Callus formation

Question 38

What is the type of repair in the Liver?

Answer 38

``` Acute = Regeneration Chronic = Cirrhosis ```

Question 39

What is the type of repair in the CNS?

Answer 39

It has no regenerative capacity, BUT glial cells can proliferate

Question 40

What is the type of repair in the smooth muscle?

Answer 40

Scarring due to them being permanent cells

Question 41

What is the type of repair in skeletal muscle?

Answer 41

Limited regenerative capacity due to satellite cells.

Question 42

What are Satellite cells?

Answer 42

Specialised Schwann cells.

Question 43

What type of degeneration occurs in peripheral nerves?

Answer 43

Wallerian degeneration

Question 44

When does Wallerian degeneration occur?

Answer 44

When a peripheral nerve is severed through damage.

Question 45

What does Wallerian degeneration cause?

Answer 45

Atrophy of the nerve axon