Week 7 Healing & cell injury & neoplasia

Question 1

Tissue response to injury

Answer 1

1. Acute inflammation
2. Demolition
   3, Healing and repair (stimulus removed)
3. Resolution

Question 2

Events in repairing

Answer 2

1. Replacement of lost tissue by granulation tissue

2. Granulation tissue matures and forms fibrous tissue (scar)

Question 3

3 types of cells according to regenerative capacities

Answer 3

1. Labile cells - continually dividing
2. Stable cells - normal proliferative activity, capable of dividing during injury
3. Permanent cells - terminally differentiated, non-proliferative

Question 4

Mechanisms of wound healing

Answer 4

1. Migration and regeneration of parenchymal cells
2. Migration and proliferation of connective tissue cells
3. Synthesis of extracellular matrix proteins
4. Remodelling of connective tissue and parenchyma
5. Collagenization and acquisition of wound strength

Question 5

4 stages of healing for skin wounds

Answer 5

1. Formation of scab and acute inflammation
2. Regeneration of epithelial covering and formation of granulation tissue in underlying connective tissue stroma
3. Deposition of collagen and resorption of capillaries
4. Formation of scar

Question 6

Healing of bone fractures

Answer 6

1. Haematoma formation and inflammation
2. Demolition
3. Callus formation (new bone)
4. Formation of lamellar bone (stronger, replace callus)
5. Remodelling

Question 7

Differences between primary intention and secondary intention healing

Answer 7

Healing by primary intention:
clean incision wound, minimal scarring

Healing by secondary intention:

1. open wound
2. greater tissue loss
3. more granulation tissue needed -> larger scar
4. more liable to infection
5. more inflammatory exudate and necrotic tissue to be removed
6. wound contraction needed
7. slower process

Question 8

Components of granulation tissue

Answer 8

1. Proliferating capillaries - supplies nutrients and oxygen
2. Fibroblasts and myofibroblasts - produce connective tissue stroma
3. Macrophages

Question 9

Factors influencing wound healing

Answer 9

Local factors: type of wound, blood supply, presence of foreign body in wound, infection, etc

General adverse factors:

1. poor nutrition
2. steroid administration
3. systemic diseases

General enhancing factor:
UV light

Question 10

Are cartilage and tendons capable of regenerating?

Answer 10

Cartilage: poor
Tendon: good but slow

Question 11

How can peripheral nerves be repaired?

Answer 11

1. Wallerian degeneration - total degeneration of axon and secondary demyelination in the distal area of transection
2. Regeneration by Schwann cell proliferation and sprouting of axons from surviving neurons

Question 12

2 important properties of stem cells

Answer 12

1. Self-renewal

2. Asymmetric division

Question 13

3 Sources of stem cells

Answer 13

1. Adult (e.g. marrow, blood, skin)
2. Embryonic
3. Induced pluripotent

Question 14

3 Important processes underlying wound healing

Answer 14

1. Growth factor
2. Cell-cell and cell-matrix interaction
3. Extracellular matrix synthesis and collagenization

Question 15

3 Main determinants of final outcome of wound

Answer 15

1. Regenerative capacity of constituent cells
2. Type and extent of injury
3. Extent of damage to extracellular matrix

Question 16

Pathogenesis of cell injury

Answer 16

1. Biochemical alterations
2. Ultrastructural changes
3. Light microscopic changes
4. Gross morphologic changes

Question 17

Causes of cell injury

Answer 17

1. Hypoxia
2. Physical agent
3. Chemical agent
4. Biological agent
5. Immunological reaction
6. Others: genetic defects, nutritional imbalance

Question 18

Determinants of result of cell injury

Answer 18

1. Injury: type, duration, severity

2. Cell: type, state, adaptability

Question 19

4 Types of Reversible cell injury

Answer 19

1. Intracellular oedema
2. Fatty change - abnormal accumulation of fat inside cell (large fat vacuole displaces nucleus to periphery)
3. Hyaline degeneration
4. Intracellular accumulation

Question 20

What are the alternative names for reversible and irreversible cell injuries?

Answer 20

Reversible injury: cell degeneration

Irreversible injury: cell death

Question 21

Mechanism of apoptosis

Answer 21

1. DNA fragmentation by endonuclease
2. Condensation and shrinkage of nucleus and cytoplasm -> form apoptotic bodies
3. Phagocytosed by adjacent cells

Question 22

Causes of apoptosis

Answer 22

Physiological causes:

1. programmed cell death during embryonic devleopment
2. normal cell turnover

Pathological causes:

1. UV / ionizing radiation
2. drugs
3. tumour cell death
4. cell-mediated immunity

Question 23

2 Ways for cells to die in necrosis?

Answer 23

1. Autolysis - release of lysosomal hydrolases from necrotic cells -> self digestion
2. Heterolysis - digested by immigrant leukocytes

Question 24

Nuclear changes during necrosis

Answer 24

1. Pyknosis - dark nucleus due to condensation of DNA
2. Karyorrhexis - fragmented nucleus
3. Karyolysis - complete dissolution of nucleus

Question 25

2 main behavioural characteristics of malignant tumour

Answer 25

1. Invasion into surrounding tissues

2. Distant metastases

Question 26

6 Types of necrosis according to morphology

Answer 26

1. Coagulative Necrosis
2. Liquefaction Necrosis
3. Caseous Necrosis (TB)
4. Enzymatic Fat Necrosis
5. Traumatic Fat Necrosis
6. Fibrinoid Necrosis