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Pathology 1 > regeneration in tissue repair > Flashcards

regeneration in tissue repair Flashcards

1
Q

regeneration in tissue repair occurs in tissues comprised of?

A

labile (epitheium) and stable cells (parenchymal organs)

-CT framework must be intact

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2
Q

scar formation is the replacement of ____ cells with?

A

replace parenchymal cells with CT

8 severe or persistent tissue injury with damage to both parenchymal cells and stromal framework

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3
Q

scar formation steps

A

1) angiogenesis
2) migration and proliferation of fibroblasts
3) deposition of CT
4) maturation and reorganization of fibrous tissue

**accumulation of CT matrix= scarring (dense fibrosis)

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4
Q

scar formation repairs begin when? granulation begins?

A

repair begins within 24 horus

*granulation tissue within 3-5 days

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5
Q

angiogenesis

A

CRITICAL for healing! MUST HAVE!

  • development of collateral circulation at sites of ischemia
  • tumor growth
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6
Q

Healing by first intention (primary union)

A

most ideal situation

  • *clean, uninfected surgical incision
  • epithelial regeneration predominates over fibrosis
    1) 24 hours: PMN migration toward clot
  • –increase mitotic activity of basal cells
    2) 24-48 hours: migration and proliferation of epithelial cells, deposition of BM components
    3) PMNs replaced by macrophages, granulation tissue, collagen at margin of incision, ep proliferation
    4) day 5: granulation tissue fill incision, collagen more abundant, normal ep thickness
    5) second week: continued collagen accumulation
    6) 1st month: scar comprises CT surfaced by ep, destruction of dermal appendage
  • TENSILE STRENGTH increases
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7
Q

Healing by second intention (secondary union)

A
  • more extensive tissue loss and inflammation
  • more granulation= more scarring
  • LARGER defect > necrotic debris > exudate fibrin > inflammation
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8
Q

what are factors that influence repair?

A

1) infection
- - most common cause of delayed wound healing
2) nutrition
3) glucocorticoids
4) mechanical factors
5) poor perfusion
- -NEED oxygen
6) foreign bodies in area
7) fibrosis associated with chronic inflammation disease
8) cirrhosis, pulmonary fibrosis, rheumatoid arthritis
9) persistent fibrogenesis +/- collagen degradation

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9
Q

keloids

A

exuberant collagen, more of an issue in asian/africans

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10
Q

list growth factos in cell regeneration and fibrosis

A
  • epidermal growth factor (EGF)
  • platelet-derived growth factor (PDGF)
  • fibroblast growth factor (FGF)
  • transforming growth factor beta (TGF-beta)
  • vascular endothelial growth factor (VEGF)
  • cytokines IL-1 and TNF
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11
Q

epidermal growth factor (EGF)

A

mitogenic factor for epithelial cells and fibroblasts

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12
Q

platelet-derived growth factor (PDGF)

A

important in activating endothelial and smooth muscle cells to produce new vessels
-induction of fibroblast, smooth muscle cell, and monocyte migration and proliferation

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13
Q

fibroblast growth factor (FGF)

A

stimulate new vessel formation

-recruits macrophages and fibroblasts to site of injury, angiogenesis

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14
Q

transforming growth factor beta (TGF-beta)

A

principally responsible for the fibrosis that accompanies chronic inflammatory states

  • low conc. (indirectly mitogenic), contributes to fibrosis
  • high conc. (inhibits growth) blocks expression of PDGF receptors
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15
Q

vascular endothelial growth factor (VEGF)

A

promotes angiogenesis, especially in neoplasms

-tumor angiogenesis and healing wounds

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16
Q

cytokines IL-1 and TNF

A

stimulates fibroblasts

-IL-1 and TNF stimulate fibroblasts, collagen production

17
Q

two processes that are involved in tissue repair

A

1) regeneration of injured tissue by the SAME type

2) replacement by CT (fibrosis)–> scar

18
Q

of cells in a tissue = rate at which

A

cells enter and exit the population

  • entry depends on proliferation rate
  • exit depends on cell death or differenciation
19
Q

what is the most important regulatory control of growth in cell cycle?

A

the induction of of resting cells (G0) from outside the cycle

20
Q

what is the cell cycle

A

1) G1 - presynthetic growth
2) S - DNA synthesis
3) G2 - premitotic growth
4) M - mitosis
5) G0 - quiescent cells

21
Q

labile cells

A
  • continuously dividing and dying
  • regenerate from stem cells
  • stem cell division = one daughter cell retains capacity to divide, the other differentiate
22
Q

stable cells

A
  • quiescent or low level replicative cells
  • parenchyma of most colid glandular organs
  • can be called upon to enter cell cycle
  • *parenchyma of most colid organs (kidney, liver, pancreas)
23
Q

permaent cells

A
  • terminally differentiated and non-proliferative postnatally
  • neurons, cardiac muscle, skeletal muscle
  • injury = sacr formation
  • *skeleta/cardiac muscle (limited regenerative capacity)
24
Q

stem cells

A
  • replenish cells of continuously dividing tissues
  • embryonic stem cells are pluripotent
  • regenerative medicine
25
Q

properties of stem cells

A

1) self renewal capacity

2) asymmetric replication

26
Q

1) autocrine signaling
2) paracrine
3) synaptic
4) endocrine

A

1) SELF
- -soluble mediators act on cell that secrets it
2) NEIGHBOR
- -mediators affect cells in immediate vicinity
3) NERVE SYNAPSE
- -activated neural tissue secretes transmitters at a synapse onto target
4) hormones released into bloodstream act on DISTANT cells

27
Q

relationship between singnaling molecules conc and affinity

A

indirect

*low conc = high affinity and specific for target cell receptor binding

28
Q

cell surface vs intracellular receptors

A

intracellular receptors= associated with DNA, receptor ligand enters cell, Vit D.steroid.thyroid/hormones

cell surface= bind to ligend, cascade of intraecellular events, increase intracellular C++, cyclic AMP, activation of repression, PROTEIN

29
Q

describe growth factors

A
  • pleiotropic
  • stimulate protooncogenes
  • expansion of cell populations
30
Q

extracellular matrix

A

dynamic, constantly changing, support for soft tissues

31
Q

interstitial matrix

A

present between cells in CT

  • 3D amoirphous gel
  • synthesized by mesenchymal cells
  • fibrillar and nonfibrillar collagens
32
Q

basement membrane

A
  • highly organized
  • beneath epithelium, synthesized by epithelium and mesenchymal cells
  • type 4 collagen, adhesive proteoglycans

Pathology 1 (21 decks)

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