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CMBM 3 > Tissue Repair > Flashcards

Tissue Repair Flashcards

1
Q

How is tissue repair defined?

A

restoration of tissue architecturally and functionally

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2
Q

Tissue repair can occur via what two mechanisms?

A

regeneration of the injured tissue
replacement of lost tissue
(part of each two mechanisms play vary from tissue to tissue)

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3
Q

Both mechanism require:

A
  • cell proliferation

- interaction between cells and the presence of intact or altered extracellular matrix

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4
Q

Compare HAV to HBV.

A

HAV (no chronic HepA)

  • hepatic necrosis
  • recover or die
  • not destroying hepatocyte

HBV (chronic Hep B)
- kills hepatocyte and matrix

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5
Q

Describe cell proliferation.

A

Continuously proliferating cells can easily regenerate after injury or being used

  • contains pools of stems cells close by
  • immune + for CD34, CD117, Ki67
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6
Q

What is totipotent cell?

A

cell can differentiate into any cell type

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7
Q

Where is the first checkpoint?

A

G1/S - check for DNA damage

-may undergo apoptosis if defect

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8
Q

Where is the second checkpoint?

A

G2/M

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9
Q

What three groups are tissues of the body divided?

A 
Continuously dividing (labile) - skin basal, GI, hair [short G0]
Stable tissues - liver, kidney, lung alveoli, bond, breast, endocrine, adipose [ long G0]
permanent - neurons in CNS, ganglia in PNS, cardiac, skeletal muscle [cannot divide]
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10
Q

Where are the three sites of stem cells in the skin?

A

epidermis
sebaceous gland
hair follicle bulge

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11
Q

Haematopoietic stem cells can differentiate into ?

A

RBC, WBC (lymphocyte, monocyte, eosinophil, basophil, neutrophil) , platelets

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12
Q

What is the actions of growth factors?

A

stimulate cell division and proliferation

promote cell differentiation & survival

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13
Q

What is EGF?

A

epithelial growth fact

mitogenic for skin & fibroblasts

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14
Q

What is TGF?

A

transforming growth factor

hepatocytes & epithelials

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15
Q

What is PDGF?

A

platelet derived growth factor
smooth muscle mitogens
cytokines

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16
Q

Cytokines can be present in which instances?

A

injured tissue remnant
inflammatory cells, macrophages, vascular endothelial cells
cytokines from fibroblasts

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17
Q

Where are cytokines stored?

A

extracellular matrix

  • basement membrane
  • interstitial matrix
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18
Q

What purpose does the basement membrane and interstitial matrix serve?

A
  • sequesters water and minerals from circulation
  • stores presynthesized growth factors
  • give cells a scaffolding upon which to adhere and do their assigned tasks
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19
Q

What is the consequence if the ECM is destroyed?

A

can’t regenerate tissue

-scar forms instead

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20
Q

What does the ECM regulate?

A

proliferation, movement, and differentiation of the cells

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21
Q

What are the stages of tissue repair?

A

regeneration

scarring

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22
Q

Where does regeneration occur frequently?

A

labile tissues

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23
Q

Where does regeneration occur to a limited extent>

A

stable tissues

  • kidney (if removed the other one undergoes hypertrophy and hyperplasia)
  • liver (remove part of liver, some will grow back)
24
Q

Describe the theoretical aspect of injury.

A

Blood clots and releases growth factors

  • Inflammation
  • granulation tissue
  • wound contraction
25
Q

At what point can regeneration not happen?

A

severe injury

26
Q

What four components to scarring are mediated by GFs?

A
  • new vessel formation (angiogenesis) VEGF
  • fibroblast proliferation elaborating FGF, TGF
  • fibroblast form an immature scar Type 1 collagen
  • fibroblast remodeling with mature scar Type 4 collagen
27
Q

What cells come in by 24 hours when an injury occurs?

A

PMNs

  • endothelial cells are called upon to start proliferating
  • fibroblasts emigrate-myofibroblasts appear wound contaction
28
Q

With what growth factor does heeling begin with ?

A

PDGF

29
Q

What happens by 3-5 days after an injury?

A

granulation (scab, eschar) tissue present

- new scaffolding upon which repair cells work

30
Q

How is the scar remodeled over time?

A

granulation tissue changing with collagen types moving from type 1 to 4

31
Q

Granulation tissue contains cross linked collagen. (T/F)

A

false; mainly blood vessels and fibrin

32
Q

What is a trichrome stain?

A

stains collagen blue/green

33
Q

Two types of wound healing

A

healing by first intention (a surgical incision)

healing by second intension (a third degree burn)

34
Q

Describe scarring with 1st intention? 2nd intention?

A

1- small scarring

2- large scarring

35
Q

How is healing by first intention accomplished?

A

epithelial regeneration predominates over fibrosis

- healing is faster with minimal scarring if no infection

36
Q

Describe the immediate timeline of first intention.

A

Vasoconstriction - blood fills incision site, platelets activated
Platelets are irritated and release clotting factors.
-also release activation factors that activate edge of wound.

37
Q

Describe the timeline changes one sees by 24 hours.

A

By 24 hours

  • platelet aggregates
  • release PDGF’s
  • migration of cells first neutrophils then macrophages come in
  • at the cut edge of lesion, stem cells are stimulated to propogate
  • chemotaxasis takes place
38
Q

Describe the timeline changes one sees by 3-7 days.

A

Macrophages come in very few PMN
Granulation tissue is formed:
- new blood vessels (VGF)
- fibroblasts (fgf) & myofibroblasts (TGF)
Collagen type 1 begins to bridge incision
very labile wound

39
Q

Describe timeline changes weeks later.

A

Granulation tissue gone, ECM back
Collagen is remodeled type IV
epidermis full thickness, mature (w/o dermal appendage)
Fibrous union

40
Q

Scars are prone to develop cancer due to lack of?

A

melanin

41
Q

Describe healing by second intention.

A

wounds that have large gaps
-race between epithelial cell and fibroblasts
- fibrosis predominated over epithelial regeneration
- healing is slower with MORE inflammation
-granulation tissue formation and scarring
-more wound contraction
Ex) ischemic necrosis (infarction)
large burns and ulcers

42
Q

What is gliosis?

A

scar in brain

43
Q

How can an infarct in the brain cause epilepsy?

A

glial cells contract leading to epilepsy

44
Q

How do skin ulcers appear?

A

slide, large gap between edges

surface is hyperkeratonized

45
Q

At the time of suture removal the tensile strength is?

A

only 10% of what is was before injury

46
Q

What is the wound strength of primary intention at third month?

A

70-80%

47
Q

What are examples of wounds gone bad due to aberrant cell growth of ECM?

A

keloid scar

proud flesh

48
Q

Why do wounds go bad?

A 
Extrensic factors trauma
acute and chronic infection
diabetes
steroids
ischemia - lower extremity heals slower than upper
personal care
radiation
diet
49
Q

Why could tissue be so vulnerable to trauma?

A

blood supply is not adequate

50
Q

What is a keloid scar?

A

hypertonic fibroblastic response
during maturation creates an overgrowth of type 1 collagen and overabundance of type IV
main proliferation below epithelium

51
Q

What is proud flesh?

A

hypertonic granulation tissue

pyogenic granuloma

52
Q

Scarring can lead to what adverse effects?

A

contraction –permanent dysfunction

53
Q

What is cirrhosis?

A

fibrosis and regenerative nodules

54
Q

Nephrosclerosis contains decreased what?

A

glomeruli

55
Q

What is a tampanade?

A

blood escapes heart and fills pericardium

56
Q

When is the heart most prone to rupture after an M.I?

A

1st week

57
Q

What atypical collagen is laid down in scars caused by cancer?

A

type V

CMBM 3 (28 decks)

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