Wound Healing

Question 1

Define wound healing.

Answer 1

Restoration of tissue architecture and function after an injury

Question 2

What is the difference between wound healing and wound repair?

Answer 2

Healing = complete restoration of tissue

Repair = incomplete restoration

Question 3

What are the steps of wound healing model?

Answer 3

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

Question 4

What are the three cell types in our body?

Answer 4

1. Labile cells
2. Permanent cells
3. Stable cells

Question 5

What are examples of labile cells? Can they regenerate?

Answer 5

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

Question 6

What are examples of stable cells? Can they regenerate?

Answer 6

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

Chance of regeneration is good

Question 7

What are examples of permanent cells? Can they regenerate?

Answer 7

Neurons
Cardiac muscle
Skeletal muscle

Heals by scarring

Question 8

What enables a tissue to undergo regeneration?

Answer 8

Presence of stem cells

Question 9

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

Answer 9

The extent of damage

Question 10

What are the three phases of healing?

Answer 10

1. Inflammatory
2. Proliferative
3. Remodeling (maturation)

Question 11

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

Answer 11

Clot formation, chemotaxis

Usually first week

Question 12

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

Answer 12

• Re-epithelialization
• Angiogenesis
• Provisional matrix

Second week

Question 13

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

Answer 13

Collagen matrix
Wound contraction

Third week

Question 14

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

Answer 14

VEGF–macrophages secrete this

Question 15

What are the two major events that happen in angiogenesis?

Answer 15

Capillary budding

Endothelial cell proliferation

Question 16

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

Answer 16

Macrophage, since is secretes cytokines ike VEGF

Question 17

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

Answer 17

TGF-beta–macrophages

Question 18

What are the two major events that occur in fibrogenesis?

Answer 18

1. Fibroblast activation/proliferation

2. Collagen deposition

Question 19

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

Answer 19

Collagenase

Elastase

Question 20

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

Answer 20

Nitric acid

ROS

Question 21

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

Answer 21

**TGF-beta**
IL-1
TNF
KGF-7
PDGF

Question 22

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

Answer 22

VEGF
FGF-2
PDGF

Question 23

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

Answer 23

TGF-beta
PDGF
TNF
IL-1
MMPs

Question 24

What is the time frame for secretion of granulation tissue?

Answer 24

3-5 days

Question 25

What is the difference between granuloma and granulation tissue?

Answer 25

Granulation tissue = tissue surrounding granuloma, that is NOT macrophages

Question 26

What is histological characteristic of granulation tissue? (3)

Answer 26

Proliferation of fibroblasts new thin walled capillaries loose ECM

Question 27

What does granulation tissue result in?

Answer 27

Fibrosis (scarring)

Question 28

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

Answer 28

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

Question 29

Is granulation tissue permanent?

Answer 29

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

Question 30

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

Answer 30

More

Question 31

How do scars appear histologically?

Answer 31

Light eosinophilic tissue relative to surrounding tissues

Question 32

What is the stain that highlights collagen? Color?

Answer 32

Trichrome stain = blue

Question 33

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

Answer 33

skin is opposed (think sutures)

Question 34

What predominates in primary intention: epithelial regeneration or fibrosis?

Answer 34

Epithelial regeneration

Question 35

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

Answer 35

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

Question 36

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

Answer 36

Primary are well apposed, secondary are not

Question 37

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

Answer 37

Secondary has large tissue defects/has more necrotic debris

Question 38

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

Answer 38

More granulation tissue in secondary

Question 39

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

Answer 39

Myofibroblasts may cause contraction in secondary

Question 40

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

Answer 40

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

Question 41

What type of wounds are contractures seen in particularly?

Answer 41

Serious burns

Question 42

What are the two places where contractures are particularly problematic?

Answer 42

Around joints In any opening (stenosis)

Question 43

What are myofibroblasts, and what is their function?

Answer 43

Hybrid of fibroblasts and smooth muscle Can secrete collagen, and contract

Question 44

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

Answer 44

Localized Ischemia

Question 45

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

Answer 45

Vit C deficiency

Question 46

What is the most common cause of delayed wound healing?

Answer 46

Infection

Question 47

What are the three pathologic aspects of repair?

Answer 47

1. Keloids 2. Exuberant granulation tissue 3. Contractures

Question 48

What is "proud flesh"?

Answer 48

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

Question 49

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

Answer 49

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

Question 50

What is a hypotrophic scar?

Answer 50

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

Question 51

What is a hypertrophic scar?

Answer 51

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

Question 52

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

Answer 52

Keloid grow beyond the scar border, and occurs later Hyper are raised within the scar margins.

Question 53

What is proud flesh? Is this conducive to healing?

Answer 53

When granulation tissue grows out too exuberantly, and PROTRUDES from the wound This is not conducive to healing

Question 54

What are the two processes involved in regeneration?

Answer 54

Proliferation | Migration

Question 55

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

Answer 55

Keloids have a haphazard arrangement of collagen, few myofibroblasts Hypertrophic scars have numerous myofibroblasts, collagen oriented parallel to skin surface