8 Repair and regeneration Flashcards Preview

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Flashcards in 8 Repair and regeneration Deck (15)
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1
Q

Differentiate between regeneration and repair of damaged tissue.

A

Regeneration: cells replaced by like, tissue returns to normal, specialised function resumes.
Repair: cells cannot be replaced by like, granulation tissue, results in fibrosis and scarring, loss of specialised function.

2
Q

What is a labile cell population?
Regenerative capacity?
Example?

A

High normal turnover with active cell population.
Excellent.
Epithelia.

3
Q

What is a stable (quiescent) cell population?
Regenerative capacity?
Examples?

A

Low turnover that can massively increase if needed.
Good.
Liver, renal tubules.

4
Q

What is a permanent cell population?
Regenerative capacity?
Examples?

A

No physiological turnover, log lived cells.
None.
Neurons, muscle cells.

5
Q

What are the architectural considerations involved in tissue regeneration?

A

Rebuilding of complex architecture is limited (glomeruli, lung).
The extent of the survival of connective tissue framework.

6
Q

What are the controlling factors in regeneration? (3)

A

Covering of defect.
Contact inhibition between cells.
Growth factors, cell-cell and cell–matrix interactions.

7
Q

Granulation tissue results in wound contraction during repair. What three functions allow this?

A

Endothelial cell proliferation forms new vessels.
Phagocytes remove dead/damaged tissue.
Myofibroblasts proliferate and migrate, synthesise collagen and ECM, yielding contractile ability.

8
Q

How do the properties of granulation tissue change as it matures?
And over what time scale?

A

Decreasing vascularity and cellularity.
Increasing collagen, extracellular matrix, and wound strength.
3 months.

9
Q

Factors that inhibit healing.

A

Infection, haematoma, blood supply, foreign bodies, mechanical stress.
Age, drugs, anaemia, diabetes, malnutrition, catabolic states, Vit C/trace metal deficiency,

10
Q

When does healing by first intention occur?

A

Clean uninfected surgical wound with good haemostats, and edges apposed by sutures/staples.

11
Q

When does healing by second intention occur and how is it different to first intention?

A

Wound edges not apposed (tissue loss, haematoma, infection, foreign body).
More florid granulation tissue reaction and more extensive scarring.

12
Q

At which day are sutures typically taken out?

A

Day 7.

13
Q

How do bone fractures heal?

A

Organised haematoma with removal of necrotic fragments. Osteoblasts lay down woven bone (callus), which remodels according to mechanical stress. replaced by lamellar bone.

14
Q

How does brain tissue heal?

A

Gliosis.
Neural tissue is terminally differentiated and the only supporting tissue is glial cells. Damaged tissue is removed, leaving a cyst.

15
Q

Which growth factors are involved in wound healing? (7)

A
EGF (epidermal)
TGF-α (transforming).
TGF-β (transforming)
PDGF (platelet derived)
KGF (keratinocyte)
TNF (tumour)
VEGF (vascular endothelial)