Tissue Repair and Healing

Question 1

What are the main cell types in tissue healing?

Answer 1

1. Macrophages, platelets, lypmphocytes, others
2. Fibroblasts
3. Endothelial cells, pericytes
4. Epithelial cells

Question 2

Which type of cells make proper cytokine milieu to promote healing?

Answer 2

Macrophages, platelets, lymphocytes, others

*Cytokines include: TGFB, PDGF, ANF, VEGF, EGF, others

Question 3

Which type of cells produces matrix metalloproteinases to digest matrix proteins in tissue healing?

Answer 3

Macrophages, platelets, lymphocytes, others

Question 4

What type of cells phagocytose and eliminate foreing material, debris in tissue healing?

Answer 4

Macrophages

Question 5

Which cells make collagen and the rest of extracellular matrix?

Answer 5

Fibroblasts

Question 6

Which cells are associated with contractile myofibroblasts that shrink wounds?

Answer 6

Fibroblasts

Question 7

Which cells make new blood vessels?

Answer 7

Endothelial cells, pericytes

Question 8

Which cells migrate and proliferate to cover wound or regenerate organ?

Answer 8

Epithelial cells

Question 9

What are the steps in tissue healing

Answer 9

1. Inflammatory response, clotting factors leak in
2. Clot forms (seconds to minutes)
3. Fibroblasts, endothelial cells, pericytes, and new epithelium migrate into clot form granulation tissue and new epithelium (days–very weak)
4. Granulation tissue matures, forming scar with mature vessels and abundant collagen (10% of normal strength at 1 week)
5. Scar matures-Collagen remodeling, loss of excess blood vessels (months to years, 70-80% of normal strength at 3 months)

Question 10

What are the different possible outcomes of repair after an inflammatory state?

Answer 10

1. Complete or to a normal state
2. Forms a scar at the site of inflammation (happens in damage too severe for simple regeneration)
3. Forms a cavity, usually in the brain or lung

Question 11

What are some general problems in tissue repair?

Answer 11

1. Process is slow
2. Too much tissue repair
3. Too little tissue repair

Question 12

In what ways in the repair process slow?

Answer 12

1. About 10% strength in 1 week
2. About 70-80% strength at most after several months
3. Often leaves a scar, not as strong as normal tissue

Question 13

Under what circumstances would you see too much tissue repair causing a problem?

Answer 13

1. Secondary intention
2. Infection
3. Clinical setting

Question 14

Under what circumstances would Too little tissue repair be a problem?

Answer 14

1. Steroids
2. Poor perfusion
3. Diabetes
4. Malnutrition, vitamin deficiency (esp. Vit. C)
5. Infection
6. Type and site of injury
7. Mechanical stress
8. Foreign bodies

Question 15

What problems does Too much repair cause?

Answer 15

1. Hypertrophic scar
2. Keloid (extends beyond the site of injury)
3. Desmoid/Fibromatosis (a benign neoplasm)

Question 16

What problems could Too little tissue repair cause?

Answer 16

1. Wound dehiscence
2. Ulcer
3. Cardiac rupture after infarct

Question 17

T/F It takes weeks for Glomeruli to regenerate after scarring

Answer 17

FALSE, Once lost to scarring, glomeruli do not regenerate