Healing And Repair

Question 0

3 components of fibrous repair?

Answer 0

Cell migration, angiogenesis, extracellular matrix

Question 1

Define resolution

Answer 1

Subsidence of a pathological state

Question 2

What cells are involved in fibrous repair?

Answer 2

Inflammatory cells such as neutrophils and macrophages
Chemical mediators such as lymphocytes and macrophages
Endothelial cells for angiogenesis
Fibroblasts and myoblasts for production of extracellular proteins like collagen and for wound contraction

Question 3

What is fibrous repair?

Answer 3

Replacement of functional tissue by scar tissue

Question 4

Why is angiogenesis important?

Answer 4

Provides access to the wound for cells

Delivers oxygen and nutrients

Question 5

What induces endothelial proliferation (therefore angiogenesis)

Answer 5

Proangiogenic growth factors such as VEGF

Question 6

Why is the extracellular matrix important in fibrous repair?

Answer 6

Supports and anchors cells
Separates tissue compartments
Sequesters growth factors 
Allows communication between cells
Facilitates cell migration

Question 7

Describe synthesis of collagen

Answer 7

Polypeptide α chains synthesised in the ER
Cleavage of signal peptide
Hydroxylation of proline/lysine residues
Addition of N-linked oligosaccharides
Disulphide bond formation
Procollagen triple helix formed by cross linking of α chains
O-linked glycosylation
Golgi then soluble procollagen secreted
Removal of terminal peptidases to produce tropocollagen
Lateral aggregation to form fibrils which bundle into fibres
Slow remodelling by specific collagenases

Question 8

Describe fibrous repair

Answer 8

Inflammatory cells infiltrate
Blood clot forms
Acute inflammation around the edges
Macrophages and lymphocytes migrate into the clot - chronic inflammation 
Clot is replaced by granulation tissue
Angiogenesis
Myo/fibroblasts migrate and differentiate 
They produce extracellular matrix
Maturation occurs

Question 9

What happens in maturation?

Answer 9

Cell population falls
Collagen increases, matures and remodels
Myofibrils contract to reduce volume of defect
Vessels differentiate and are reduced
Left with a fibrous scar

Question 10

What is granulation tissue made out of?

Answer 10

Capillary loops and myofibroblasts

Question 11

What causes fibrosis?

Answer 11

Macrophages releasing pro-fibrotic cytokines causing fibroblast proliferation

Question 12

Define regeneration

Answer 12

Replacement of dead/damaged cells by functional, differentiated cells.

Question 13

In regeneration, where are the regenerated cells derived from?

Answer 13

Stem cells

Question 14

What does unipotent mean? (In relation to stem cells)

Answer 14

Only produce one type of differentiated cell eg epithelia

Question 15

What does multi potent mean?

Answer 15

Can produce several types of cells eg haemopoietic

Question 16

What does totipotent mean?

Answer 16

Can produce any type of cell eg embryonic stem cells

Question 17

What are labile cells? Example

Answer 17

They are in state of rapid division and constantly in the cell cycle
Epithelial cells

Question 18

What are stable cells? Example?

Answer 18

Normally in resting G0 stage but can exit this if damage occurs
Hepatocytes, osteoblasts, fibroblasts

Question 19

What are permanent cells? Example?

Answer 19

Constantly in G0 so cannot regenerate

Neurones

Question 20

What are factors controlling regeneration?

Answer 20

Growth factors

Contact of the cell between basement membrane and adjacent cells

Question 21

How do growth factors control regeneration?

Answer 21

Promote proliferation in the stem cell population

Promote expression of genes controlling the cell cycle

Question 22

How does contact with basement membrane/adjacent cells control regeneration?

Answer 22

Signalling through adhesion molecules inhibits proliferation in intact tissue
Contact inhibition
Loss of contact promotes proliferation

Question 23

List some LOCAL factors that influence efficacy of healing and repair

Answer 23

Type, size and location of the wound
Apposition and lack of movement
Blood supply - arterial or venous
Infection
Foreign material
Radiation damage

Question 24

List some systemic factors that influence efficacy of healing and repair

Answer 24

Age
Drugs (steroids) and hormones
General dietary deficiencies such as protien, zinc, vit C and amino acids
Chronic diseases
Cardiovascular status

Question 25

What happens of there is chronic damage to the liver?

Answer 25

Cirrhosis

Question 26

Outcome if there is damage to cardiac muscle?

Answer 26

Fibrosis

Question 27

Outcome if there is damage to bone?

Answer 27

Callus formation

Question 28

Outcome of there is damage to peripheral nerves? (Go over in text book)

Answer 28

Wallerian degeneration

Proximal degeneration, distal proliferation

Question 29

Outcome of damage to CNS?

Answer 29

No regenerative capacity

Glial cells can proliferate - gliosis

Question 30

Outcome of there is damage to smooth muscle?

Answer 30

Replaced by scar tissue

Vascular smooth muscle has some limited regeneration

Question 31

Outcome if there is damage to skeletal muscle?

Answer 31

Satellite cells can carry out limited regeneration

Question 32

Describe process of angiogenesis

Answer 32

Proteolysis of basement membrane by endothelial cells
Chemotaxis of endothelial cells
Endothelial proliferation
Endothelial maturation and tubular remodelling
Recruitment of periendothelial cells