Tissue Renewal

Question 1

What factors control wound healing in a healthy individual?

Answer 1

1. Extent and location of injury
2. Interactions between ECM and cellular modulator of repair.
3. Tissue capacity for regeneration

Question 2

Differentiate Regeneration from repair

Answer 2

Regeneration: Replacement by normal cells
Repair: Replacement by fibrosis and scar tissue

Question 3

Describe the effects of superficial injury

Answer 3

No damage to underlying tissues; resolves by regeneration

Question 4

Describe the effects of severe injury

Answer 4

Damage to underlying CT; Repaired by scar formation

Question 5

What is the role of the basement membrane?

Answer 5

Separates cells that synthesize it from adjacent tissues.

Question 6

What is the role of the provisional matrix?

Answer 6

1. Binds stroma to reduce blood loss

2. Provides support for cells migrating to repair site; fibrinogen, fibronectin

Question 7

What are the growth factors of angiogenesis and proliferation?

Answer 7

Angiogensis: VEGF, FGF
Proliferation: PGDF, EGF

Question 8

Which cells migrate into a wound and what is their function?

Answer 8

PMNs: Invade in first 24 hrs and release ROS
Macrophages: Arrive after PMNs and persist, phagocytose debris

Question 9

How does the type and extent of tissue injury affect repair?

Answer 9

Complete restoration can only occur in stable and labile cell tissues; Injury to permanent cells causes scarring

Question 10

How does location of the injury affect repair?

Answer 10

Inflammation in tissue spaces or cavities develop extensive exudates; Repair involves digestion of exudate followed by resorption

Question 11

What are the 4 phases of wound healing?

Answer 11

1. Hemostasis
2. Inflammation
3. Proliferation-Granulation
4. Remodeling maturation

Question 12

Compare wound healing by second intention to first intention.

Answer 12

1. Defect is larger
2. Fibrin-rich scab is larger
3. More necrotic debris
4. Inflammatory response is more intense

Question 13

What factors can retard repair process?

Answer 13

1. Infection
2. Steroids: inhibit TGF-B and fibrosis
3. Mechanical factors
4. Nutritional status

Question 14

What is wound dehiscence?

Answer 14

Splitting open of a wound.

Question 15

Discuss keloids

Answer 15

Scars the progress beyond the injured site; Irregular collagen bundles with abnormally high amounts of fibroblasts histologically

Question 16

What causes strictures?

Answer 16

Contractures that obstruct the passage of food through the esophagus or intestines.

Question 17

What is an adhesion?

Answer 17

Fibrous bands that form between tissues or organs during wound healing

Question 18

How does an adhesion form?

Answer 18

When fibrinolysis is impaired, proliferating fibroblasts to invade and leave deposits of collagen and ECM materials.

Question 19

What is a fistula?

Answer 19

An abnormal tube-like passage between 2 viscous organs.