Pathology Week 5 E

Question 1

Define resolution:

Answer 1

The healing outcome in which a tissue is restored to its pre injury state

Question 2

What 3 events usually occur during resolution?

Answer 2

Liquefaction

Removal of products of liquefaction

Removal of remaining particulate matter

Question 3

When does resolution occur?

Answer 3

When only a few cells are lost/ only a small injury

Question 4

When does regeneration occur? How does it occur?

Answer 4

When there is extensive cellular damage

It occurs with the replacement of lost cells

Question 5

What must happen before regeneration can occur?

Answer 5

The site of trauma must be cleared

Question 6

What are labile cells? Example.

Answer 6

Cells which divide actively throughout life, replacing cells which are normally lost. Eg. Skin cells

Question 7

What are stable cells? Example. What do they require for regeneration?

Answer 7

Cells with a long life span and low rate of division. They are mature, differentiated, functioning cells.Found in areas such as liver and pancreas.Need an adequate connective tissue framework for regeneration

Question 8

What are permanent cells? Example.

Answer 8

Have no capacity for mitotic division in post natal life.Eg. Neurons, myocardial cells

Question 9

What is primary intention healing?

Answer 9

A healing process which occurs when a small number of cells is lost

Question 10

What is secondary intention healing?

Answer 10

A healing process which occurs when a large number of cells is lost

Question 11

What are the 2 phases of primary intention healing?

Answer 11

Preparative phase

Reparative phase

Question 12

What happens in the preparative phase of primary intention healing? What are the events?

Answer 12

The wound is stabilised.

The events are:

• wound defect is filled with blood
• acute inflammation
• bleeding is arrested (platelets, clotting proteins)
• scab formation
• clot retraction draws the edges of the wound together.

Question 13

What is the purpose of a scab? 5 P’s

Answer 13

Prevents further blood loss

Pulls wound edges together

Prevents dehydration

Prevents entry of micro organisms

Protection against physical irritation

Question 14

What can fibronectin bind to?

Answer 14

Collagen

Fibrin/fibrinogen

Proteoglycan

Cell surfaces

Bacteria

Question 15

What are the events that occur in the epidermis in the reparative phase of primary intention healing?

Answer 15

Increased mitosis and budding of basal cells resulting in bridging of wound deficit.Growth and migration of local epithelial cells help to fill tissue deficit and restore epithelial continuity

If damage to the basal layer was minimal then epithelial architecture is normal

Question 16

What are the events that occur in the epidermis in the reparative stage of primary intention healing?

Answer 16

1. Migration and division of fibroblasts
2. Invasion of wound by fibroblasts
3. Collagen synthesis and deposition by fibroblasts
4. Gradual strengthening (maturation) of scar tissue (eg collagen cross linking)

Question 17

What is difference between the preparative phases of primary and second intention healing?

Answer 17

Nothing except that the process in secondary intention healing is much more extensive, intense and longer lasting

Question 18

In the reparative phase of secondary intention healing what are the events that occur in the epidermis?

Answer 18

Restoration of epithelial continuity is initially not possible as the tissue deficit cannot be bridged by cellular budding (bridge formation). Also no formation exists for epithelial cells to migrate over.

Question 19

In the reparative phase of secondary intention healing what are the events that occur in the dermis?

Answer 19

1. Development of granulation tissue
2. Gradual strengthening of scar tissue
3. Granulation tissue serves as a foundation for the spread of epithelial cells but loss of normal epidermal architecture results at the site of healing. Thus skin overlying the scar does not look normal
4. Scar devascularisation occurs (scar colour changes from pink to white)

Question 20

What are the events of granulation tissue formation?

Answer 20

1- migration and division of fibroblasts

2- invasion of wound defect by fibroblasts

3- invasion of wound defect by capillaries

4- collagen synthesis and deposition by fibroblasts

Question 21

What are the events of strengthening of scar tissues?

Answer 21

1- collagen cross-linking

2- type I collagen replaces type II

3- alignment of collagen fibres along stress lines

4- achievement of maximum scar strength in approximately 6 months.

Question 22

What are the main contributors to wound contraction?

Answer 22

Collagen

Myofibroblasts

Question 23

What are myofibroblasts? What do they do?

Answer 23

Specialised myofibrils containing fibroblasts

Undergo contraction of actomyosin filaments early in wound contraction

Cause early contraction of wound

Question 24

What are the effects of collagen cross linking and condensation?

Answer 24

Wound contraction

Increased tensile strength and flexibility of scar

Question 25

What are factors which impede healing?

Answer 25

• Ongoing infection
• Clotting abnormalities
• Poor overall health status
• Suppressed immunity
• Mechanical irritation
• Poor blood supply
• Inadequate nutrition

Question 26

Summary of events in secondary intention healing:

Answer 26

1. Bleeding
2. Clot and scab formation
3. Intense inflammatory/ exudative phase
4. Restoration of epithelial continuity cannot occur as it needs a foundation to grow across
5. Granulation tissue develops
6. Progressive collagen deposition, devascularisation and wound contraction.
7. Scar tissue maturation

Question 27

Define contractures

Answer 27

When tissues surrounding a large wound are mobile and are gradually drawn in by the contracting scar