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Pathology > Wound Healing > Flashcards

Flashcards in Wound Healing Deck (55)
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1
Q

Define wound healing.

A

Restoration of tissue architecture and function after an injury

2
Q

What is the difference between wound healing and wound repair?

A

Healing = complete restoration of tissue

Repair = incomplete restoration

3
Q

What are the steps of wound healing model?

A
  1. Damage
  2. Inflammation
  3. Removal of dead tissue
  4. Replacement by 4.scar or tissue
  5. =healing
4
Q

What are the three cell types in our body?

A
  1. Labile cells
  2. Permanent cells
  3. Stable cells
5
Q

What are examples of labile cells? Can they regenerate?

A

Cells that have high turnover rate, like epithelium. Chance of regeneration is excellent

6
Q

What are examples of stable cells? Can they regenerate?

A

Cells that normally do not undergo proliferation, but remain capable of cell division.

Chance of regeneration is good

7
Q

What are examples of permanent cells? Can they regenerate?

A

Neurons
Cardiac muscle
Skeletal muscle

Heals by scarring

8
Q

What enables a tissue to undergo regeneration?

A

Presence of stem cells

9
Q

What determines if a tissue that is able to undergo regeneration undergoes scarring?

A

The extent of damage

10
Q

What are the three phases of healing?

A
  1. Inflammatory
  2. Proliferative
  3. Remodeling (maturation)
11
Q

What are the two events that occur during inflammation? When does this occur?

A

Clot formation, chemotaxis

Usually first week

12
Q

What are the three events that happen in proliferation? When does this occur?

A
  • Re-epithelialization
  • Angiogenesis
  • Provisional matrix

Second week

13
Q

What are the two events that occur in the maturation (remodeling) stage

A

Collagen matrix
Wound contraction

Third week

14
Q

What is the major molecule that signals angiogenesis? What cell secreted this?

A

VEGF–macrophages secrete this

15
Q

What are the two major events that happen in angiogenesis?

A

Capillary budding

Endothelial cell proliferation

16
Q

What cell is the “director” of wound healing? Why?

A

Macrophage, since is secretes cytokines ike VEGF

17
Q

What is the major chemical in fibrogenesis? What cells secrete this?

A

TGF-beta–macrophages

18
Q

What are the two major events that occur in fibrogenesis?

A
  1. Fibroblast activation/proliferation

2. Collagen deposition

19
Q

What are the two enzymes secreted by macrophages that facilitate debridement of tissue/debris?

A

Collagenase

Elastase

20
Q

What are the two types of chemicals secreted by macrophages that have an antimicrobial activity?

A

Nitric acid

ROS

21
Q

What are the five chemicals secreted by macrophages that promote chemotaxis?

A
**TGF-beta**
IL-1
TNF
KGF-7
PDGF
22
Q

What are the three chemicals secreted by macrophages that stimulate angiogenesis?

A

VEGF
FGF-2
PDGF

23
Q

What are the five chemicals secreted by macrophages that signal for deposition and remodeling of the ECM?

A
TGF-beta
PDGF
TNF
IL-1
MMPs
24
Q

What is the time frame for secretion of granulation tissue?

A

3-5 days

25
Q

What is the difference between granuloma and granulation tissue?

A

Granulation tissue = tissue surrounding granuloma, that is NOT macrophages

26
Q

What is histological characteristic of granulation tissue? (3)

A

Proliferation of fibroblasts
new thin walled capillaries
loose ECM

27
Q

What does granulation tissue result in?

A

Fibrosis (scarring)

28
Q

What is the difference of early vs late stage granulation tissue?

A

Late = Less vascular, only scattered macrophages, more matrix and fibroblasts

29
Q

Is granulation tissue permanent?

A

No, just trying to cover damage until collagen can be deposited

30
Q

The (BLANK) granulation tissue, the more contraction, and the greater risk of organ impairment.

A

More

31
Q

How do scars appear histologically?

A

Light eosinophilic tissue relative to surrounding tissues

32
Q

What is the stain that highlights collagen? Color?

A

Trichrome stain = blue

33
Q

What is the first (primary) intention of skin healing?

A

skin is opposed (think sutures)

34
Q

What predominates in primary intention: epithelial regeneration or fibrosis?

A

Epithelial regeneration

35
Q

What is a 2nd intention healing? What does this lead to?

A

When edges cannot be lined up. This leads to more granulation tissue = more fibrosis

36
Q

What is the difference between first and second intention healing in terms of wound apposition?

A

Primary are well apposed, secondary are not

37
Q

What is the difference between first and second intention healing in terms of necrotic debris, exudate, and fibrin to be removed?

A

Secondary has large tissue defects/has more necrotic debris

38
Q

What is the difference between first and second intention healing in terms of granulation tissue

A

More granulation tissue in secondary

39
Q

What is the difference between first and second intention healing in terms of myofibroblast wound contraction?

A

Myofibroblasts may cause contraction in secondary

40
Q

What is wound contraction? What cell type is responsible for this?

A

Reduction in the size of a wound that is healed by second intention. Myofibroblasts in the granulation tissue

41
Q

What type of wounds are contractures seen in particularly?

A

Serious burns

42
Q

What are the two places where contractures are particularly problematic?

A

Around joints

In any opening (stenosis)

43
Q

What are myofibroblasts, and what is their function?

A

Hybrid of fibroblasts and smooth muscle

Can secrete collagen, and contract

44
Q

What is the cause of decubitus ulcers (bed sores)?

A

Localized Ischemia

45
Q

What is the nutritional deficiency that can lead to ineffective healing?

A

Vit C deficiency

46
Q

What is the most common cause of delayed wound healing?

A

Infection

47
Q

What are the three pathologic aspects of repair?

A
  1. Keloids
  2. Exuberant granulation tissue
  3. Contractures
48
Q

What is “proud flesh”?

A

When wounds may generate excessive granulation tissue in healing, preventing wound closure

49
Q

What are the histological characteristics of a keloid? (what is and is not there compared to normal)

A

Dermis replaced by an irregularmeshwork of collagen w/o many cells, and lacking glands and hair follicles

50
Q

What is a hypotrophic scar?

A

Scar that have a sunken appearance and hyperpigmentation d/t loss of collagen and ground substance

51
Q

What is a hypertrophic scar?

A

Similar to keloid, but does not get worse beyond 6 months, and does not recur

52
Q

What is the clinical difference between hypertrophic scars, and keloid scars?

A

Keloid grow beyond the scar border, and occurs later

Hyper are raised within the scar margins.

53
Q

What is proud flesh? Is this conducive to healing?

A

When granulation tissue grows out too exuberantly, and PROTRUDES from the wound

This is not conducive to healing

54
Q

What are the two processes involved in regeneration?

A

Proliferation

Migration

55
Q

What is the histological difference between keloids and hypertrophic scars? (hint, collagen, and myofibroblasts)

A

Keloids have a haphazard arrangement of collagen, few myofibroblasts

Hypertrophic scars have numerous myofibroblasts, collagen oriented parallel to skin surface