healing and repair Flashcards

1
Q

What will contribute to resolution rather than repair?

A
  1. initiating factor removed

2. tissue undamaged/able to regenerate

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2
Q

What will lead to repair rather than resolution?

A
  1. initiating factor still present

2. tissue damaged and unable to regenerate

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3
Q

What are the features of repair?

A
  1. replacement of damaged tissue by fibrous tissue

2. the collagen is produced by fibroblasts

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4
Q

Give examples of repair

A
  1. heart after myocardial infarction
  2. brain after cerebral infarction
  3. spinal cord after trauma
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5
Q

Which cells can regenerate?

A
hepatocytes
pneumocytes
all blood cells 
gut epithelium
skin epithelium
osteocytes
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6
Q

Which cells do not regenerate?

A

cardiac myocytes
neurones
(striated muscle cells)

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7
Q

What two pt populations suffer with poor wound healing?

A

elderly

diabetics

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8
Q

What is healing?

A

restoration with no/minimal residual defect:

  • superficial skin abrasion
  • healing by 1st intention
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9
Q

Is healing by second intention classified as healing or repair?

A

repair

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10
Q

Describe healing from skin abrasion

A
  1. cells proliferate and spread out as a thin sheet until the defect is covered
  2. stimulus to proliferate is switched off by contact inhibition
  3. epidermis is rebuilt from the base upwards
    the scale is a layer of fibrin that protects the epidermis as it grows
    cells from sweat glands and hair follicles can contribute to healing
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11
Q

What is organisation?

A

repair of specialised tissues by the formation of a fibrous scar

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12
Q

What happens in organisation?

A
  1. granulation tissue is formed and then contracts and accumulates collagen to form a scar
  2. dead tissue is removed by phagocytosis
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13
Q

what is granulation tissue made of and how is it formed?

A

capillary loops and myofibroblasts
capillary endothelial cells proliferate and grow into the area
fibroblasts divide and secrete collagen and ECM
collagen forms a scar

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14
Q

why does a wound contract?

A

Contraction of myofibroblasts in granulation tissue to reduce the volume tissue for repair

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15
Q

What is a disadvantage of granulation tissue?

A

contraction of scar tissue around a lumen causes stenosis/stricture and contracture in muscles

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16
Q

Explain healing by first intention

A
  • made by a scalpel
  • causes little damage to tissues on either side of the cut
  • the two sides of the wound are brought together accurately
  • coagulated blood forms a scab and helps keep the wound clean
  • capillaries proliferate
  • fibroblasts secrete collagen
  • only the elastin in the dermis is not restored
  • a thin layer of fibrin joins the edges. This is replaced by collagen and covered by epidermis
17
Q

Explain healing by second intention

A
  • happens when there is tissue loss
  • this prevents the two sides of the wound coming together
  • phagocytosis to remove debris
  • granulation tissue to fill in defects
  • epithelial regeneration to cover surface
18
Q

why does liver cirrhosis result?

A

The hepatocytes AND the architecture have been damaged

19
Q

Vascular smooth muscle cannot be regenerated as muscle is a permanent population. T or F?

A

False

20
Q

What happens when peripheral nerves are damaged?

A

Wallerian degeneration