10. The Tissue Reapir Process/ Defects In Tissue Repair Process

Question 1

Regeneration in Mild tissue injury

Answer 1

Rebuilding by proliferation of surviving cells and maturation of tissue stem cells

Question 2

Connective tissue fibrosis formation in severe injury

Answer 2

Chronic inflammation or extensive ischemic necrosis leads to excess collagen deposition-fibrosis

Question 3

Tissue proliferation activity

Answer 3

Labeled - cells proliferate through life (bone marrow hematopoietic cells)

Stable- low-level replication, but capable of rapid Divison in response to injury (liver, kidney)

Permanent - cannot divide (heart, brain)

Question 4

Factors affecting the outcome of healing process

Answer 4

Proliferation capacity of damaged tissue

Integrity of ECM

Existence of chronic inflammation

Question 5

Steps in repair by scar formation

Answer 5

1. Inflammation (6-48 hours) - macrophages major players
2. Cell proliferation (up to 10 days) - epithelial cells respond to growth factors and migrate over, angiogenesis occurs ( new blood vessel production) proliferating fibroblasts produce new collagen fibers and granulation tissue - epithelial cells that can proliferate through a growth factor
3. Remodeling of connective tissue (2-3 weeks) - replacement of granulation tissue with fibrous scar (TGF-B involved in synthesis and deposition of connective tissue proteins)

Question 6

Factors that influence tissue repair

Answer 6

Systemic: nutritional, metabolic, circulatory, hormones (glucocorticoids)

Local: infections, size and location, mechanical forces and foreign bodies

Question 7

Venous leg ulcer

Answer 7

Common in elderly

Result of chronic venous hypertension

Persistent inflammation

Question 8

Diabetic foot ulcer

Answer 8

Due to hyperglycemia

Question 9

Arterial ulcer

Answer 9

Reduced blood supply

Ischemia/necrosis

Common in diabetics

Question 10

Pressure sore

Answer 10

Tissue necrosis

Prolonged soft tissue compression

Local ischemia

Question 11

Hypertrophic scars

Answer 11

Excessive collagen formation forms raised scar along site of injury

Question 12

Keloid

Answer 12

Progression beyond area of injury

Question 13

Excessive granulation

Answer 13

Blocks reepithelization

Looks like meatballs

Question 14

Formation of contractures

Answer 14

Exaggerated wound process results in deformity

Question 15

Fibrosis in organs

Answer 15

Excessive deposits of collagen and other ECM components

Pathological process and is usually associated with loss of function/ organ dysfunction

Not normal-gives organ structural support

Question 16

Mechanism of fibrosis

Answer 16

1. Persistence/severe tissue injury leads to chronic inflammation
2. Cytokines (TGF-B) stimulate the migration and proliferation of fibroblasts
3. Deposits of collagen and other ECM proteins