Chapter 3- Tissue Renewal, Regen And Repair

Question 1

What is the difference between tissue regeneration and repair?

Answer 1

Regen- complete reconstitution, structures return to normal (ECM remains intact)

Repair- some deficits (scar formation), damage beyond basal layer

Question 2

What are the functions of the ECM?

Answer 2

Framework for cell migration

Maintenance of cell polarity

Formation of new blood vessels

Production of GFs, cytokines, chemokines

Question 3

What is normal cell proliferation regulated by?

Answer 3

Rates of:
Cell proliferation

Cellular differentiation

Apoptotic death

Question 4

What are characteristics of labile tissues?

Answer 4

Can regenerate as long as stem cell pool is preserved, asymmetric division

Question 5

What types of tissues are labile?

Answer 5

Epithelium, GI Tracy, oral cavity, ducts

Question 6

What are the characteristics of quiescent/stable tissues?

Answer 6

Rest in G0 stage but capable of entering the cell cycle, limited capacity to regenerate

Question 7

What types of tissues are quiescent?

Answer 7

Parenchyma of most solid organs

Question 8

What are the characteristics of permanent tissues?

Answer 8

Terminally differentiated and non-proliferative, limited stem cells reproduction, not sufficient for regen

Question 9

What types of tissues are permanent?

Answer 9

Neurons and cardiomyocytes

Question 10

What drives proliferation?

Answer 10

Signals from GFs and ECM

Question 11

What is an important source of GFs?

Answer 11

Activated macrophages

Question 12

What is required for restoration of normal tissues?

Answer 12

Residual scaffolding must be intact

Question 13

What are the phases of liver regeneration?

Answer 13

Priming- Kuppfer cells produce cytokines, hepatocytes can respond to GFs

GF phase- cells enter G1 and replicate

Termination phase- return to quiescence

Question 14

What are the characteristics of repair by connective tissue deposition?

Answer 14

Chemokine release

Acute inflammation

Angiogenesis

Granulation tissue formation

Connective tissue remodelling

Question 15

What is severe, chronic damage to connective tissue/non-dividing cells associated with?

Answer 15

Repair by connective tissue deposition

Question 16

What factors influence tissue repair?

Answer 16

Infection (prolongs)

Diabetes (limits blood flow)

Nutritional status (vit C deficiency and collagen)

Glucocorticoids (anti-inflam)

Mechanical factors

Poor perfusion

Foreign bodies

Type and extent of injury

Question 17

What is the difference between primary and secondary union (healing by first or second intention)?

Answer 17

Primary- clean, uninfected wound, minimal fibrosis

Secondary- large, cutaneous ulcer, more inflammation, parenchymal and strongly damage

Question 18

What are the steps of wound healing?

Answer 18

1. Coagulation (clot is scaffolding)
2. Neutrophils migrate
3. Macrophages dominate
4. Granulation tissue fills space (fibroblast migration, ECM proteins and collagen produced)
5. Scar retracts

Question 19

What is fibrosis?

Answer 19

Excessive collagen deposition, usually due to persistent, injurious stimuli, associated with loss of tissue

Question 20

What disorders may be associated with fibrosis?

Answer 20

Liver cirrhosis

Systemic sclerosis/scleroderma

Idiopathic pulmonary fibrosis

Pneumoconioses

Question 21

What can result due to inadequate formation of granulation tissue?

Answer 21

Wound dehiscence (rupture)

Ulceration (inadequate vascularization)

Question 22

What can result due to excessive formation of repair process components?

Answer 22

Hypertrophic scar (deep layers of dermis involved)

Keloid- hypertrophic scar grows beyond wound boundaries

Question 23

What is exuberant granulation?

Answer 23

Proud flesh

Granulation tissue protrudes above surrounding skin

No actual scar