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Intro to path > Tissue healing and repair 08 22 14 > Flashcards

Tissue healing and repair 08 22 14 Flashcards

1
Q

regeneration

A

growth of cells and tissues to replace lost structures
usually what happesn to labile cells
no scar

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2
Q

healing with scar formation

A

occurs when complete restitution is not possible

usually collagen (fibrosis) gives structural support

usual response to severe/chronic damage in lung, liver, kidneys

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3
Q

components of tissue repair after injury

A

remnants of injured tissue
endothelial cells
fibroblasts

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4
Q

how are dead cells replaced in labile and stable tissues after injury?

A

stem cells undergo asymmetric replication

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5
Q

what growth factors induce angiogenesis in tissue repair?

A

vascular endothelial growth factors VEGF

fibroblast growth factors FGF

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6
Q

what growth factors induce production of ECM in tissue repair?

A

platelet-derived growth factors PDGF

transforming growth factor-beta TGF-beta

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7
Q

two forms of ECM

A

interstitial matrix

basement membrane

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8
Q

role of ECM

A

mechanical support

regulate cell proliferation (through integrins)

PROVIDES SCAFFOLD essential for healing without scar

storage of growth factors-fibroblast growth factor, hepatocyte growth factor

creates microenvironment

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9
Q

components of ECM

A

fibrous structural proteins: collagen and elastin

proteoglycans and hyaluronans-highly hydrated gels for compressibility

adhesive glycoproteins and receptors (fibronectin, laminin, adhesion molecules)

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10
Q

Ehlers Danlos syndrome

A

genetic defect in collagen synthesis or structure

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11
Q

Marfan syndrome

A

mutation affecting fibrillin-a major compoentn of microfibrils in ECM

so results in:
degeneration of aorta (aneurysm and dilatation)
dislocated lens
long legs, arms, fingers

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12
Q

repair by connective tissue (scar formation) occurs when?

A

severe or chronic tissue injury w/ destruc of stroma

injury of non-dividing cells

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13
Q

4 sequential steps of repair by connective tissue (scar formation)

A

angiognenesis
fibroblast migration and proliferation
ECM deposition (scar formation)
maturation of fibrous tissue (remodeling)

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14
Q

granulation tissue

A

specialized tissue in healing

present by 3-5 days (with new vessels, inflammatory cells, fibroblasts)

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15
Q

what causes vasodilatation for angiogenesis in tissue repair?

A

NO

vascular endothelial growth factor VEGF

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16
Q

where are the cells from angiogenesis for tissue repair coming from?

A

endothelial precursor cells (angioblasts) in bone marrow

17
Q

what cellse secrete growth factors to promote fibroblast migration to site of injury and proliferation?

A

endothelium and inflammatory cells

18
Q

what growth factors are involved in fibroblast migration and proliferation and deposition of ECM?

A

FGF
PDGF
TGF-beta

19
Q

how does degradation of collagen and other extracellular matrix proteins occur in the remodeling of the scar?

A

matrix metalloproteinases (MMP) containing zinc

20
Q

3 phases of cutaneous wound healing

A

inflammation
granulation tissue formation and re-epithelialization
wound contraction, ECM deposition and remodeling

21
Q

healing by first intention steps

A

immediate: incisional space fills with clotted blood

within 24 hrs: neutrophils appear, begin re-epithelialization

by day 3: neutrophils replaced by macrophages, granulation tissue fills incisional space

day 5: maximal granulation tissue, collagen fibers begin to bridge incision

weeks: scar (connective tissue w/o inflam), decreased vessels

22
Q

healing by secondary intention ex

A

large wounds (wide, not just deep)
abscesses
ulceration

23
Q

healing by secondary intention definition

A

more intense inflam due to large firin clot and more necrotic material to be removed

larger amt of granulation tissue

WOUND CONTRACTION by myofibroblasts

substantial scar formation with THINNED EPIDERMIS

24
Q

wound strength becomes 70-80% of uninjured tissue at what time post injury?

A

third month

25
Q

what can influence tissue healing?

A

nutrition: vit C deficiency impairs collagen synthesis

metabolic status: diabetic pts have impaired neutrophil and macrophage fxns, impaired new vessel formation, impaired collagen syn—persisting ulcers and infec

circulatory status: poor perfusion impairs healing

hormones: steroids inhibit TGFbeta, decreases fibrosis
infection: prolongs inflam and may increase local injury

mechanical factors: increased local pres may cause closed wound to rupture

foreign bodies: prolongs inflam

26
Q

keloid

A

raised scar due to excess collagen, is covered by epithelium

27
Q

exuberant granulation

A

wound protrudes above surrounding skin and prevents re-epithelialization so NOT covered unlike keloid

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