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CMBM exam 3 > Tissue repair > Flashcards

Tissue repair Flashcards

1
Q

What does it mean to repair a tissue?

A

Both restoration of tissue architecture and function after an injury
Complete recovery rarely achieved

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2
Q

What are the two mechanisms of tissue repair?

A

Regeneration of injured tissue

Replacement of lost tissue

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3
Q

Which mechanism of tissue repair require cell proliferation of intact or altered cellular matrix?

A

Both

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4
Q

Stem cells produce a baseline cell population which do ____ or ____.

A

Proliferate, die via apoptosis

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5
Q

What are the types of continuously dividing (labile) cells?

A

Skin basal, hematopoietic, hair follicles and GI cells

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6
Q

What does the G0 phase look like for the continuously dividing cells?

A

Short

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7
Q

What are the stable cells and what does it mean to be stable?

A

Liver, kidney, lung alveoli, bone, breast, endocrine, adipose, vessels
Only need to proliferate when necessary

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8
Q

What does the G0 phase look like for stable cells?

A

Long

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9
Q

What are the permanent tissues and what does that mean?

A

Neurons in CNS, ganglia in PNS, cardiac, skeletal muscle

Cannot divide functionally

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10
Q

What are some characteristics of continuously generating cells?

A

Can easily regenerate after injury with a infinite life span
Dependent on age and health
Contains pools of stem cells
Immune positive for CD34, CD117, Ki67

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11
Q

What are the three locations for skin stem cells?

A

Epidermis, sebaceous gland, hair follicle bulge

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12
Q

What are the actions of growth factor?

A

Stimulate cell division and proliferation

Promote cell differentiation and survival

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13
Q

What some examples of growth factors?

A

Epithelial growth factor (skin, fibroblasts)
Transforming growth factor (hepatocytes, epithelials)
Platelet derived growth factor (s muscle, cytokines)
Erythropoietin
Granulocyte growth factor

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14
Q

What does each growth factor have on its target cell?

A

A specific receptor

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15
Q

When cells are injured and proliferate what is released?

A

Cytokines

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16
Q

Where do the cell injury responsive cytokines come from?

A

Damaged tissue, inflammatory cells, macrophages and vascular endothelial cells and fibroblasts

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17
Q

What are the two forms of the extracellular matrix?

A

Interstital matrix and basement membrane

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18
Q

What does the extracellular matrix do?

A

Sequesters water and mineral from circulation
Stores presynthesized growth factors
Gives cells a scaffolding upon which to adhere and do their assigned tasks

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19
Q

What does the ECM regulate overall?

A

Proliferation, movement, and differentiation of cells living in or on it

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20
Q

If the ECM is completely destroyed what happens?

A

It cannot regenerate and a scar forms

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21
Q

When does regeneration occur in labile tissues?

A

All the time, can make as much as needed

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22
Q

When does regeneration occur in stable tissue?

A

A limited extent, only some can come back or compensate for lost tissue
Only occurs if the residual tissue is healthy and intact

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23
Q

When does regeneration occur in permanent tissue?

A

Pretty much never and will always form scar tissue

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24
Q

What are the steps to injury healing?

A
  1. Cut
  2. Inflammation
  3. Blood clotting
  4. Granulation tissue - scab,eschar
  5. Wound contraction
  6. Wound recovery
  7. Scar tissue
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25
Q

If an injury is too severe…

A

regeneration can’t happen

26
Q

What are the four components used in regeneration mediated by growth factor?

A

New vessel formation VEGF
Fibroblast proliferation FGF, TGF
Fibroblast synthesis of immature scar - type 3 collagen
Fibroblast remodeling with mature scar - type 1 collagen

27
Q

What is an eschar?

A

A scab

28
Q

Granulation tissue does not contain….

A

Cross linked collagen

29
Q

What are the three examples of wound healing?

A

First intention - sew shut
Second intention - leave open
Third degree burn

30
Q

What does it mean when a wound is healed by first intention?

A

Occurs in small wounds that close easily
Suturing or butterfly tape possible to use
Epithelial regeneration predominates over fibrosis
Healing is fast, minimal scarring
well vascularized, no dead tissue

31
Q

What is the time line to see changes for first intention healing?

A

Immediately
By 24 hours
By 3-7 days
Weeks later

32
Q

During the phase of immediate healing for first intention, what is seen?

A 
Vasoconstriction - platelet activation
Vasodilation - fills with blood
Blood clots 
release of mediators - PDGF
Fibrinogen in blood converted to Fibrin by platelets 
Temporary scaffold
33
Q

What happens in 24 hours in first intention wound healing?

A 
Platelets aggregate
Release PDGF's and firm clot formation
Migration of cells first of neutrophils and then macrophages 
In Cut edges, stem cells wake up
Chemotaxasis
34
Q

By 3-7 days what has happened in first intention wound healing?

A 
More macrophages with few PMN
Granulation tissue formed - new blood vessels, fibroblasts (acted on by TGF) & myofibroblasts
Collagen type 1 begins to bridge 
ECM starts to be made
Newly made epithelium thickens
35
Q

What happens after a few weeks in first intention wound healing?

A

Granulation tissue gone; ECM back
Collagen type IV
Epidermis full thickness
Little scar forms

36
Q

What happens in healing by second intention?

A

Large wound gap occurs and fibrosis predominates over epithelial regeneration
Healing is slower, more inflammation, granulation of tissue formations and scaring (less wound contraction)

37
Q

Why can good wounds (that could heal well) go bad?

A

Trauma, acute or chronic infection, diabetes, steroids, ischemia, radiation

38
Q

What is a keloid scar?

A

Hypertrophic fibroblast response (more collagen)

too much type 1 leads to too much type 4 collagen

39
Q

What is a proud flesh scar?

A

Hypertrophic granulation tissue (more vessels present)

also called Pyogenic granuloma

40
Q

When is a scar good and when is it bad?

A

Good - forms well and is resilient

Bad - permanent contraction dysfunction

41
Q

How does HBV lead to scarring but HAV not?

A

HBV injures the matrix as well which leads to scarring

HAV only damages the cells

42
Q

what can store cytokines?

A

extracellular matrix

43
Q

what does basement membrane consist of?

A

Type IV collagen
Laminin
Proteoglycan

44
Q

what does interstitial matrix consist of?

A

fibrillar collagens
Elastin
Proteoglycan
Hyaluronan

45
Q

what mediates the process of Scarring?

A

Growth factors

  1. New vessel formation (angiogenesis) by VEGF
  2. Fibroblast proliferation elaborating FGF, TGF
  3. Fibroblast synthesis of immature scar - Type 1 collagen
  4. Fibroblast remodeling with mature scar - Type 4 collagen
46
Q

After a cut, a clot forms and within seconds

A

heeling begins with PDGF

47
Q

Fibrinogen is converted to Fibrin for

A

temporary scaffolding for WBCs

48
Q

By 24 hrs after an injury,

A

PMNs, platelets, Macs take over
Endothelial cells begin to proliferate
Fibroblasts emigrate - become myofibroblasts and wound contraction begins

49
Q

By 3-5 days after an injury,

A

granulation tissue is present
-scab, eschar
New firm scaffolding is present that repair cells can work

50
Q

Weeks after an injury

A

there is dense fibrosis - scar

scar remodeled in months from pink to white then wrinkled

51
Q

Granulation tissue has

A

no crosslinked collagen
mainly blood vessels and fibirin
no PMNs

52
Q

Examples of some injuries that heal by second intention?

A

Ischemic necrosis - infarction
large burns
Ulcers

53
Q

Ulcer caused by

A

some ischemia and pressure

54
Q

cirrhosis is

A

fibrosis and regenerative nodules

55
Q

Trichrome

A

stains collagen blue

56
Q

Proper Repair occurs

A

with architecture and function

57
Q

what collagen change is seen in breast cancer?

A

Collagen type 5 is seen

58
Q

Nephrosclerossi

A

scarring of glomeruli from hypertension induced damage

59
Q

contraction of scars in the brain leads to

A

seizures

60
Q

Lung infarctions are

A

hemorrhagic

CMBM exam 3 (24 decks)

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