Repair and Regeneration Flashcards Preview

EMS - Mechanisms of disease > Repair and Regeneration > Flashcards

Flashcards in Repair and Regeneration Deck (18):
1

What is repair?

Damaged cells cannot be replaced by like.

Fibrosis and scarring.

Loss of specialised function.

2

What is a labile cell population?

High normal turnover

Active stem cell population

Excellent regenerative capacity
- eg Epithelia

3

What are stable (quiescent) cell populations?

Low physiological turnover

Turnover can massively increase if needed

Good regenerative capacity
- eg liver, renal tubules

4

What are permanent cell populations?

No physiological turnover

Long life cells

No regenerative capacity (nb recent stem cell research)
- eg neurons, muscle cells

5

What are stem cells?

Prolonged self-renewal

Asymmetric replication

Reservoirs present in many adult tissues (‘Adult’stem cell ‘niches’)

6

What types of injury may cause the destruction of stem cells?

Full-thickness burns

Radiation

7

What processes take part in the control of regeneration?

Proliferation of stem cell / amplifying cell compartments

Covering of defect

Contact inhibition

Complex control by growth factors, cell-cell and cell-matrix interactions

8

What key things does the process of regeneration depend on?

Restoration of normal structure / function

Depends on tissue cell kinetics, architecture

Depends on stem cell survival

9

What is the name given to the tissue that eventually matures into fibrous scar tissue?

Granulation tissue

10

Describe the process of granulation.

New capillary loops form.

Phagocytic cells move into dead tissue and start clearing.

Proliferation and migration of myofibroblasts- synthesise collage and ECM.

Acquire myofibrils and contractile ability.

11

What factors may inhibit healing?

Local:
- Infection
- Haematoma
- Blood supply
- Foreign bodies

Systemic:
- Age
- Drugs (eg steroids - induce a catabolic state)
- Anaemia
- Diabetes
- Malnutrition
- Catabolic states
- Vitamin C deficiency
- Trace metal deficiency
- Mechanical stress

12

What is healing by first intention?

Clean, uninfected surgical wound

Good haemostasis

Edges apposed eg with sutures or staples

13

What is healing by second intention?

Wound edges not apposed

Extensive loss of tissue

Apposition not physically possible
- i.e. Large haematoma, infection, foreign body

More florid granulation tissue reaction (“leaving a wound to granulate”)

More extensive scarring

14

What is the healing process process for fracture?

Haematoma is organised

Removal of necrotic fragments

Osteoblasts lay down woven bone
- (=callus)

Remodelling according to mechanical stress

Replacement by lamellar bone

15

What happens when the brain tries to heal?

Neurons are terminally differentiated

Supporting tissue is glial cells rather than collagen and fibroblasts etc

Hence damaged tissue is removed, often leaving cyst

Gliosis rather than scarring

16

Which cells release epidermal growth factor and what is its function?

Macrophages, platelets

Also found in saliva and plasma.

Mitogenic to keratinocytes and fibroblasts. Stimulates granulation.

17

Which cells release transforming growth factor b and what is its function?

Released by T cells (and others probably)

Chemotactic to:
- PMNs
- macrophages
- lymphocytes
- fibroblasts
- smooth muscle cells

Stimulates:
- TIMP synthesis
- angiogenesis
- fibroplasia.

Inhibits:
- activation of MMPs
- keratinocyte proliferation

18

What is regeneration?

Normal healing.

Damaged cells can be replaced by like.

Tissue returns to normal.