Sesson 4 - Regeneration And Repair

Question 1

What are the 4 processes involved in wound healing?

Answer 1

Haemostasis
Inflammation
Regeneration or repair

Question 2

What is regeneration?

Answer 2

Regrowth of cells, minimal evidence of injury

Question 3

What kind of injuries are possible for regeneration?

Answer 3

Minor

Question 4

Where do new cells come from?

Answer 4

Stem cells

Question 5

What are stem cells?

Answer 5

Cells that can differentiate into other cell types and self renew to replace dead or damaged cells

Question 6

What are 3 types of stem cells?

Answer 6

Totipotent
Multi potent
Unipotent

Question 7

What is a totipotent stem cell?

Answer 7

Able to produce all cell types

Question 8

What is a multi potent stem cell?

Answer 8

Produce several cell types

Question 9

What is a unipotent stem cell?

Answer 9

Can produce one cell type

Question 10

What are 3 locations that stem cells can be found?

Answer 10

Basal layer of epidermis
Bottom of crypts in intestinal mucosa
Liver between hepatocytes

Question 11

What is labile tissue?

Answer 11

Continuously replicating cells

Question 12

What is stable tissue?

Answer 12

Normally low level of replication but can undergo rapid replication if needed

Question 13

What is permanent tissue?

Answer 13

Cells don’t replicate

Question 14

What is an example of labile tissue?

Answer 14

Epithelium

Question 15

What is an example of stable tissue?

Answer 15

Bone

Question 16

What is an example of permanent tissue?

Answer 16

Cardiac muscle

Question 17

Where are labile cells in the cell cycle?

Answer 17

Continuously cycling

Question 18

Where are stable cells in the cell cycle?

Answer 18

Left but can re-enter in G0

Question 19

Where are permanent cells in the cell cycle?

Answer 19

Left and cannot re enter

Question 20

What does a tissue need to regenerate?

Answer 20

Intact connective tissue architecture

Question 21

What is fibrous repair?

Answer 21

Replacement of functioning tissue with a scar

Question 22

When do labile/stable tissues undergo fibrous repair instead of regeneration?

Answer 22

When collagen framework destroyed or during on going chronic inflammation

Question 23

What are the 4 steps of scar formation?

Answer 23

Bleeding & haemostasis
Inflammation
Proliferation of fibroblasts
Remodelling

Question 24

How long does haemostasis take?

Answer 24

Seconds-minutes

Question 25

What is the purpose of haemostasis?

Answer 25

Prevention of blood loss

Question 26

What is the purpose of inflammation?

Answer 26

Digestion of blood clot

Question 27

How long does inflammation take?

Answer 27

Minutes-days

Question 28

What are the 4 things that proliferate during scar formation?

Answer 28

Capillaries Fibroblasts Myofibroblasts Extracellular matrix

Question 29

How long does proliferation take?

Answer 29

Days-weeks

Question 30

What are the 3 functions of granulation tissue?

Answer 30

Fills gap Supply oxygen and nutrients Contract and close wound

Question 31

How long does remodelling take?

Answer 31

Weeks - years

Question 32

What are the 3 processes happening during remodelling or scar maturation?

Answer 32

Reduced cell population by apoptosis Increased collagen Contraction of myofibroblasts

Question 33

What are the 4 cells involved in fibrous repair?

Answer 33

Neutrophil Macrophage Lymphocyte Endothelial cells

Question 34

What are the 2 purposes of neutrophils and macrophages?

Answer 34

Phagocytosis | Release mediators

Question 35

What are the 2 purposes of lymphocytes?

Answer 35

Eliminate pathogens | Coordinate other cells

Question 36

What are 2 microscopic features of a fibroblast?

Answer 36

Spindle shaped nucleus | Cytoplasmic extensions

Question 37

What are the 2 functions of fibroblasts?

Answer 37

Secrete collagen and elastin | Form extracellular matrix

Question 38

What is a myofibroblasts?

Answer 38

Between fibroblast and smooth muscle

Question 39

What is the purpose of myofibroblasts?

Answer 39

Expresses intracellular actin so contracts the wound

Question 40

What is 2 examples of where type 1 collagen is found?

Answer 40

Skin | Bones

Question 41

What are 2 examples of type 4 collagen can be found?

Answer 41

Basement membranes | Lens

Question 42

What are 4 stages of collagen formation

Answer 42

Pre-pro collagen = alpha chain undergoes vit C dependent hydroxylation in ER Pro collagen = alpha chains cross links and forms triple helix in cytoplasm Tropocollagen = cleaved C and N terminals in extracellular space Microfibrils, fibrils and collagen fibres = cross linked tropocollagen

Question 43

What is a acquired disease of defective collagen?

Answer 43

Scurvy

Question 44

What are 3 inherited diseases of defective collagen?

Answer 44

Ehlers-Danlos syndrome Osteogenesis imperfecta Alpert syndrome

Question 45

How are regeneration and repair controlled?

Answer 45

Cells communicate with each other to stimulate or initiation cell division

Question 46

What are 3 ways cells communicate to control proliferation?

Answer 46

Direct cell-cell contact Local mediators Hormones

Question 47

What is contact inhibition?

Answer 47

Isolated cells replicate until they encounter other cells, Cadherins bind between cells to inhibit further proliferation

Question 48

What are growth factors?

Answer 48

Polypeptides that act on cell surface, causes cell to enter cell cycle and proliferate

Question 49

What are 4 examples of growth factors?

Answer 49

Epidermal Vascular endothelial Platelet derived Tumor necrosis

Question 50

What are the 2 ways of healing of skin?

Answer 50

Primary intention | Secondary intention

Question 51

What kind of wounds heal by primary intention?

Answer 51

Apposed edges

Question 52

How does healing by primary intention happen?

Answer 52

Minimal clot and granulation tissue Epidermis regenerates Dermis undergo his fibrous repair Leaves small scar

Question 53

What kind of wound heals by secondary intention?

Answer 53

Unopposed edges with significant tissue loss

Question 54

How does healing by secondary intention occur?

Answer 54

Abundant clot, inflammation and granulation tissue Considerable wound contraction Significant repair of dermis Regeneration of epidermis

Question 55

What are 4 stages of fracture healing?

Answer 55

Hematoma formation Soft callus formation Hard callus formation Bone remodelling

Question 56

What happens during hematoma formation?

Answer 56

Granulation tissue laid down

Question 57

What happens during soft callus formation?

Answer 57

Fibrous tissue and cartilage | Woven bone

Question 58

What happens during hard callus formation?

Answer 58

Woven bone gradually organized into lamellar bone?

Question 59

What happens during bone remodelling?

Answer 59

Lamellar bone remodeled to original outline of bone

Question 60

What are 5 local factors influencing wound healing?

Answer 60

``` Size Location Blood supply Local infection Foreign bodies ```

Question 61

What are 8 systemic factors influencing wound healing?

Answer 61

``` Age Anaemia Obesity Diabetes Drugs Vitamin deficiencies Malnutrition ```

Question 62

What are 6 complications of fibrous repair?

Answer 62

``` Insufficient fibrosis Excessive fibrosis Adhesions Loss of function Disruption of architecture Excessive scar contraction ```

Question 63

What is another word for insufficient fibrosis?

Answer 63

Wound dehiscence

Question 64

What are 4 things that can lead to insufficient fibrosis or wound dehiscence?

Answer 64

Obesity Elderly Malnutrition Steroid use

Question 65

What kind of scar forms during excessive fibrosis?

Answer 65

Keloid

Question 66

What are adhesions?

Answer 66

Fibrous bands that can cause obstruction of tubes

Question 67

Why does loss of function occur due to fibrous repair?

Answer 67

Replacement of specialized tissue by fibrous tissue

Question 68

What are 2 possible consequences of excessive scar contraction?

Answer 68

Constriction of tubes | Fixed flexion deformities or contractures