Tissue Renewal Flashcards
What factors control wound healing in a healthy individual?
- Extent and location of injury
- Interactions between ECM and cellular modulator of repair.
- Tissue capacity for regeneration
Differentiate Regeneration from repair
Regeneration: Replacement by normal cells
Repair: Replacement by fibrosis and scar tissue
Describe the effects of superficial injury
No damage to underlying tissues; resolves by regeneration
Describe the effects of severe injury
Damage to underlying CT; Repaired by scar formation
What is the role of the basement membrane?
Separates cells that synthesize it from adjacent tissues.
What is the role of the provisional matrix?
- Binds stroma to reduce blood loss
2. Provides support for cells migrating to repair site; fibrinogen, fibronectin
What are the growth factors of angiogenesis and proliferation?
Angiogensis: VEGF, FGF
Proliferation: PGDF, EGF
Which cells migrate into a wound and what is their function?
PMNs: Invade in first 24 hrs and release ROS
Macrophages: Arrive after PMNs and persist, phagocytose debris
How does the type and extent of tissue injury affect repair?
Complete restoration can only occur in stable and labile cell tissues; Injury to permanent cells causes scarring
How does location of the injury affect repair?
Inflammation in tissue spaces or cavities develop extensive exudates; Repair involves digestion of exudate followed by resorption
What are the 4 phases of wound healing?
- Hemostasis
- Inflammation
- Proliferation-Granulation
- Remodeling maturation
Compare wound healing by second intention to first intention.
- Defect is larger
- Fibrin-rich scab is larger
- More necrotic debris
- Inflammatory response is more intense
What factors can retard repair process?
- Infection
- Steroids: inhibit TGF-B and fibrosis
- Mechanical factors
- Nutritional status
What is wound dehiscence?
Splitting open of a wound.
Discuss keloids
Scars the progress beyond the injured site; Irregular collagen bundles with abnormally high amounts of fibroblasts histologically
What causes strictures?
Contractures that obstruct the passage of food through the esophagus or intestines.
What is an adhesion?
Fibrous bands that form between tissues or organs during wound healing
How does an adhesion form?
When fibrinolysis is impaired, proliferating fibroblasts to invade and leave deposits of collagen and ECM materials.
What is a fistula?
An abnormal tube-like passage between 2 viscous organs.
