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Semester 2-PP > Session 4-Healing:Regeneration And Repair > Flashcards

Session 4-Healing:Regeneration And Repair Flashcards

1
Q

Which processes are involved in wound healing? (3)

A

1) Haemostasis
2) Inflammation
3) Regeneration and repair

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2
Q

What is regeneration?

A

Restitution with no, or minimal, evidence that there was a previous injury

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3
Q

What is the difference between an abrasion and an ulcer?

A

Abrasion-lose top few layers of cells, only affecting mucosa

Ulcer-injury goes into submucosa, more severe form of abrasion

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4
Q

Which cells replicate in regeneration?

A

New differentiated cells are mainly derived from stem cells

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5
Q

What are stem cells?

A

Prolonged proliferative activity and show asymmetric replication

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6
Q

Whereabouts in the epidermis are the stem cells?

A

Basal layer adjacent to basement membrane

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7
Q

Whereabouts in the intestinal mucosa are the stem cells?

A

Bottom of crypts

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8
Q

Whereabouts in the liver are the stem cells?

A

Between hepatocytes and bile ducts

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9
Q

What are the three types of stem cells?

A

1) unipotent
2) multipotent
3) totipotent

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10
Q

What are unipotent stem cells?

A

Most adult stem cells which only produce one type of differentiated cell eg. Epithelia

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11
Q

What are multipotent stem cells?

A

Produce several types of differentiated cell eg haematopoeitic stem cells

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12
Q

What are totipotent stem cells?

A

Embryonic stem cells which can produce any type of cell and therefore any tissues of the body

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13
Q

What are blood cells derived from?

A

Multipotent stem cells in bone marrow

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14
Q

Can all tissues regenerate?

A

No

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15
Q

Give examples of labile tissues and describe what they contain

A

Surface epithelia, haematopoeitic tissues

Contain short-lived cells that are replaced from cells derived from stem cells

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16
Q

Give examples of stable tissues

A

Liver parenchyma
Bone
Fibrous tissue
Endothelium

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17
Q

True or false: stable tissues have a low level of replication but if necessary can undergo rapid proliferation

A

TRUE

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18
Q

Give examples of permanent tissues

A

Neural tissue
Skeletal muscle
Cardiac muscle

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19
Q

Which type of cells are continuously cycling in the cell cycle?

A

Labile cells

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20
Q

In what circumstances can regeneration take place?

A

If damage occurs in labile or stable tissue

If tissue damage is not extensive

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21
Q

What is fibrous repair?

A

Healing with formation of fibrous connective tissue (scar)

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22
Q

When does fibrous repair occur?

A

With significant tissue loss and if permanent or complex tissue is injured

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23
Q

Which type of injury is repaired by regeneration?

A

Necrosis of labile or stable tissues if collagen framework is intact

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24
Q

Which injuries involve fibrous repair?

A

Necrosis of labile or stable tissues when collagen framework is destroyed or when there is ongoing chronic inflammation

OR

Necrosis of permanent tissues

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25
Q

During which period of scarring are stitches removed from wounds?

A

Between 7 and 10 days (early scarring)

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26
Q

When does granulation tissue form?

A

3 days

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27
Q

What does granulation tissue consist of?

A

Developing capillaries
Fibroblasts and myofibroblasts
Chronic inflammatory cells

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28
Q

What are the functions of granulation tissue?

A

Fills the gap
Capillaries supply oxygen, nutrients and cells
Contracts and closes the hole

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29
Q

What are the stages of scar formation? (6)

A

1) haemostasis
2) acute inflammation
3) chronic inflammation
4) granulation tissue forms
5) early scar
6) scar maturation

30
Q

Which inflammatory cells are involved in fibrous repair?

A

1) Neutrophils and macrophages-phagocytosis

2) Lymphocytes and macrophages-production of chemical mediators

31
Q

How are endothelial cells involved in fibrous repair?

A

They proliferate and result in angiogenesis

32
Q

How are fibroblasts and myofibroblasts involved in fibrous repair?

A

1) Produce extracellular matrix proteins eg collagen

2) Responsible for wound contraction-contraction of fibrils within myofibroblasts

33
Q

Why do scars become white?

A

No regeneration of melanocytes

34
Q

Why do scars tend to stretch with time?

A

Fibroblasts/myofibroblasts cannot lay down elastin

35
Q

Why does hair not grow on a scar?

A

Hair follicles cannot regenerate

36
Q

Which type of collagen is the most common and where is it found?

A

Type I

In hard and soft tissue (bones, tendons, ligaments, skin, sclera, cornea, blood vessels)

37
Q

What does type IV collagen make up?

A

Basement membrane

38
Q

Where are the polypeptide alpha chains of collagen synthesised?

A

In the ER of fibroblasts and myofibroblasts

39
Q

Which vitamin is needed for hydroxylation in collagen formation?

A

C

40
Q

What produces the tensile strength of collagen?

A

Cross-linking between molecules

41
Q

What causes scurvy?

A

Vitamin C deficiency

42
Q

Which collagen does scurvy affect most?

A

Collagens supporting blood vessels

43
Q

Why can scurvy lead to tooth loss?

A

Collagen in periodontal ligament has short half life and normal collagen is replaced by defective collagen

44
Q

What is Ehlers-Danlos syndrome a defect in?

A

Conversion of procollagen to tropocollagen

45
Q

Why can skin recoil in Ehlers-Danlos syndrome?

A

Elastic fibres are normal, just missing the tethering effect of normal collagen fibres

46
Q

Describe the joints of a patient with Ehlers-Danlos syndrome

A

Hypermobile

Predisposition to joint dislocation

47
Q

Why do patients with osteogenesis imperfecta have blue sclerae?

A

Too little collagen within them and they are translucent

48
Q

True or false: Alport syndrome is an X-linked disease

A

TRUE

49
Q

What abnormality results in Alport syndrome?

A

Type IV collagen abnormality

50
Q

How does Alport syndrome present in children/adolescents?

A

Haematuria progressing to renal failure
Neural deafness
Eye disorders

51
Q

Why are growth factors important?

A

Wound healing

52
Q

What are growth factors coded by?

A

Proto-oncogenes

53
Q

What do growth factors do in the cell cycle?

A

Bind to specific receptors, stimulate transcription of genes that regulate entry of cell into cell cycle and cell’s passage through it

54
Q

Apart from cell proliferation, what other effects can growth factors have?

A 
Inhibition of division
Locomotion 
Contractility 
Differentiation 
Viability 
Activation 
Angiogenesis
55
Q

Which cells produce growth factors?

A

Platelets
Macrophages
Endothelial cells

56
Q

What is contact inhibition?

A

1) signalling through adhesion molecules

2) inhibits proliferation in intact tissue, promotes proliferation in damaged tissues

57
Q

What do cadherins do?

A

Bind cells to each other

58
Q

What do integrins do?

A

Bind cells to extracellular matrix

59
Q

Describe the type of wound in primary intention

A

Incised, closed and non-infected and sutured wounds (typical surgical wound)

60
Q

What is healing by primary intention?

A

Disruption of basement membrane continuity but death of only small number of epithelial and connective tissue cells

61
Q

True or false: there is minimal clot and granulation tissue in primary intention

A

TRUE

62
Q

What occurs in healing by primary intention?

A

1) epidermis regenerates
2) dermis undergoes fibrous repair
3) minimal contraction and scarring

63
Q

Describe the type of wound in secondary intention

A

Excisional wound, wounds with tissue loss and separated edges, infected wounds eg infarct, ulcer, abscess

64
Q

What happens to the wound in secondary intention?

A

Open wound filled by abundant granulation tissue - grows in from wound margins

65
Q

True or false: circular scars heal better than rectangular ones

A

FALSE - other way round

66
Q

True or false: healing by primary intention takes longer than healing be secondary intention

A

FALSE - secondary takes longer

67
Q

Which local factors can influence wound healing? (5)

A

1) type, size and location of wound
2) mechanical stress
3) blood supply
4) local infection
5) foreign bodies

68
Q

Which general factors influence wound healing?

A

1) age
2) anaemia, hypoxia and hypovolaemia
3) obesity
4) diabetes
5) genetic disorders
6) drugs
7) vitamin deficiency
8) malnutrition

69
Q

What are the complications of fibrous repair? (6)

A

1) insufficient fibrosis
2) formation of adhesions
3) loss of function due to replacement of specialised functional parenchymal cells by scar tissue
4) disruption of complex tissue relationships within an organ
5) overproduction of fibrous scar tissue
6) excessive scar contraction

70
Q

What is a keloid scar?

A

Lots of collagen within the dermis so excessive fibrous scar tissue is produced

Semester 2-PP (13 decks)

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