repair Flashcards

1
Q

What is repair?

A

replacement of damaged tissue by new healthy one

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2
Q

What are the factors that affect repair?

A
  • local factors
  • general factors
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3
Q

What are the local factors?

A
  • severity of tissue damaged
  • state of blood supply
  • type of tissue (cell) damaged
  • presence of infection or foreign body
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4
Q

What are the general factors affecting repair?

A
  • age: repair is more rapid at young age
  • protein deficiency: delays repair
  • vitamin deficiency: vitamin C deficiency delays wound healing and vitamin D deficiency delays healing of bone fracture
  • zinc deficiency: delays wound healing
  • glucocorticosteroids: delay repair
  • diabetes mellitus: delays repair
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5
Q

What are the types of repair?

A
  • repair my regeneration
  • repair by fibrosis
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6
Q

What is repair by regeneration?

A

replacement of damaged tissue by new healthy ones of the same kind

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7
Q

Cells are divided according to their power of regeneration into…

A
  • labile cells: cells that proliferate continuously throughout life (e.g. surface epithelial cells and haemopoietic and lymphoid cells
  • stable cells: cells that divide only when needed (in response to injury) like parenchymal cells 9liver) and mesenchymal cells (fibroblasts and osteoblasts)
  • permanent cells: cells that do not divide at all like nerve and muscle
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8
Q

What are some examples of regeneration?

A
  • regeneration of skin: epidermis heals by regeneration and dermis heals by fibrosis
  • regeneration of liver cells: injury of liver cells alone without injury of supporting stroma is followed by complete and perfect regeneration while injury of liver cells and supporting stroma is followed by liver cirrhosis
  • regeneration of bone fracture
  • repair in nervous system
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9
Q

What are the stages of regeneration of bone fracture?

A
  • haematoma formation
  • traumatic inflammation
  • formation of granulation tissue
  • formation of woven bone
  • formation of cartilage
  • formation of lamellar bone
  • remodelling
  • bone marrow regeneration
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10
Q

What are the factors that may cause failure of bony union?

A
  • failure of immobilisation
  • infection at site of fracture
  • impairment of blood supply
  • nutritional and vitamin deficiencies
  • presence of soft tissue between fracture ends
  • glucocotricosteroids
  • old age
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11
Q

Is there repair in CNS?

A

no regeneration of nerve cells in bran and spinal cord and the dead cells are replaced by glial cells (gliosis)

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12
Q

Can nerve cells in peripheral nervous system repair?

A

yes

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13
Q

How is nerve cell repair in peripheral nervous system done?

A
  • axonal degeneration: affects nerve cells which swell, lose its Nissil granules and nucleus becomes eccentric
  • Wallerian degeneration: axis cylinder and myeline sheath of distal segment break into fat globules which are removed by macrophages
  • regeneration: Schwann cells of both proximal and distal segments proliferate, communicate and form an empty tube inside which the axis cylinder grows from the proximal segment at a rate of 1mm/day. If the 2 ends of the nerve are not opposite each other, proliferating Schwann cells mix with regenerating axis cylinder and form a painful mass known as traumatic (stump) neuroma
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14
Q

What is repair by fibrosis?

A

replacement of damaged tissue by granulation tissue which matures into fibrous tissue

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15
Q

When does repair by fibrosis occur?

A

healing of abscess, infarction, serofibrinous inflammation, thrombus and dermis in skin wounds

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16
Q

What is the pathogenesis of repair by fibrosis?

A

the damaged tissue is invaded by granulation tissue from surrounding living tissues (granulation tissue is formed of new capillary loops and proliferating fibroblasts)

17
Q

What are the steps of granulation tissue formation?

A
  • angiogenesis
  • fibrogenesis
  • maturation of granulation tissue
18
Q

What are the types of healing wounds?

A
  • healing by primary union
  • healing by secondary union
19
Q

What is another name for healing by primary union?

A

healing by 1st intention

20
Q

What is another name for healing by secondary union?

A

healing by 2nd intention

21
Q

When does healing by 1st intention occur?

A

surgical wounds with minimal tissue loss and edges are approximated

22
Q

When does healing by 2nd intention occur?

A

infected wounds with marked tissue loss and edges are widely separated

23
Q

In healing by primary union, wound is…

A

filled with blood clot

24
Q

In healing by secondary union, wound is…

A

filled with blood clot, pus cells and necrotic debris

25
Q

So skin appendages regenerate in any type of healing?

A

no

26
Q

The scar in healing by primary union is…

A

thin and nice

27
Q

The scar in healing by secondary union is…

A

thick and ugly

28
Q

Are complications common in primary union?

A

no

29
Q

Are complications common in secondary union?

A

yes

30
Q

What are some complications of wound healing?

A
  • chronic ulcer
  • chronic sinus
  • fistula
  • keloid
  • contraction
  • implantation epidermal cyst
  • squamous cell carcinoma
31
Q

What is chronic ulcer?

A

persistent loss of continuity of skin or mucous membrane

32
Q

What is the cause of chronic ulcer?

A

excess collagen at edges interfering with blood supply

33
Q

What is chronic sinus?

A

a blind-ended tract connecting deep wound with the surface and tract is lined by granulation tissue

34
Q

What is the cause of chronic sinus?

A

presence of foreign body or persistent infection

35
Q

What is fistula?

A

tract connecting 2 epithelial surfaces

36
Q

What causes fistula?

A

presence of foreign body or persistent infection

37
Q

What are examples of fistula?

A
  • tract between maxillary sinus and oral cavity
  • tract between trachea and oesophagus
  • tract between urinary bladder and vagina
  • tract between anal canal and peri-anal skin
38
Q

What is keloid?

A
  • large projecting scar covered by thin stretched skin
  • due to overdone repair
  • may follow healing of burns or wounds
  • more common in dark races
  • recurs after surgical removal
  • shrinks by irradiation
39
Q

What causes keloids?

A

foreign body