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CMBM exam 3 > Tissue repair > Flashcards

Flashcards in Tissue repair Deck (60):
1

What does it mean to repair a tissue?

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

2

What are the two mechanisms of tissue repair?

Regeneration of injured tissue
Replacement of lost tissue

3

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

Both

4

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

Proliferate, die via apoptosis

5

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

Skin basal, hematopoietic, hair follicles and GI cells

6

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

Short

7

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

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

8

What does the G0 phase look like for stable cells?

Long

9

What are the permanent tissues and what does that mean?

Neurons in CNS, ganglia in PNS, cardiac, skeletal muscle
Cannot divide functionally

10

What are some characteristics of continuously generating cells?

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

11

What are the three locations for skin stem cells?

Epidermis, sebaceous gland, hair follicle bulge

12

What are the actions of growth factor?

Stimulate cell division and proliferation
Promote cell differentiation and survival

13

What some examples of growth factors?

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

14

What does each growth factor have on its target cell?

A specific receptor

15

When cells are injured and proliferate what is released?

Cytokines

16

Where do the cell injury responsive cytokines come from?

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

17

What are the two forms of the extracellular matrix?

Interstital matrix and basement membrane

18

What does the extracellular matrix do?

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

19

What does the ECM regulate overall?

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

20

If the ECM is completely destroyed what happens?

It cannot regenerate and a scar forms

21

When does regeneration occur in labile tissues?

All the time, can make as much as needed

22

When does regeneration occur in stable tissue?

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

23

When does regeneration occur in permanent tissue?

Pretty much never and will always form scar tissue

24

What are the steps to injury healing?

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

25

If an injury is too severe...

regeneration can't happen

26

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

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

What is an eschar?

A scab

28

Granulation tissue does not contain....

Cross linked collagen

29

What are the three examples of wound healing?

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

30

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

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

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

Immediately
By 24 hours
By 3-7 days
Weeks later

32

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

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

33

What happens in 24 hours in first intention wound healing?

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

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

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

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

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

36

What happens in healing by second intention?

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

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

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

38

What is a keloid scar?

Hypertrophic fibroblast response (more collagen)
too much type 1 leads to too much type 4 collagen

39

What is a proud flesh scar?

Hypertrophic granulation tissue (more vessels present)

also called Pyogenic granuloma

40

When is a scar good and when is it bad?

Good - forms well and is resilient
Bad - permanent contraction dysfunction

41

How does HBV lead to scarring but HAV not?

HBV injures the matrix as well which leads to scarring
HAV only damages the cells

42

what can store cytokines?

extracellular matrix

43

what does basement membrane consist of?

Type IV collagen
Laminin
Proteoglycan

44

what does interstitial matrix consist of?

fibrillar collagens
Elastin
Proteoglycan
Hyaluronan

45

what mediates the process of Scarring?

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

After a cut, a clot forms and within seconds

heeling begins with PDGF

47

Fibrinogen is converted to Fibrin for

temporary scaffolding for WBCs

48

By 24 hrs after an injury,

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

49

By 3-5 days after an injury,

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

50

Weeks after an injury

there is dense fibrosis - scar
scar remodeled in months from pink to white then wrinkled

51

Granulation tissue has

no crosslinked collagen
mainly blood vessels and fibirin
no PMNs

52

Examples of some injuries that heal by second intention?

Ischemic necrosis - infarction
large burns
Ulcers

53

Ulcer caused by

some ischemia and pressure

54

cirrhosis is

fibrosis and regenerative nodules

55

Trichrome

stains collagen blue

56

Proper Repair occurs

with architecture and function

57

what collagen change is seen in breast cancer?

Collagen type 5 is seen

58

Nephrosclerossi

scarring of glomeruli from hypertension induced damage

59

contraction of scars in the brain leads to

seizures

60

Lung infarctions are

hemorrhagic