Wound Healing

Question 1

Name three classes of transmembrane signaling receptors and the intracellular signaling pathways that they usually activate.

Answer 1

1. Kinases
   b. Respond to grow factors
   c. Activates PI3, IP3 and MAP kinase pathways
2. Receptors without kinase activity
   a. Respond to cytokines
   b. JAK/STAT pathways
3. G-protein coupled receptors
   a. Respond to chemokines
   b. Ca2+

Question 2

Diagram the cell cycle.

Answer 2

GO
        -	Quiescent
G1
        -	Growth and centrosome replication
S
        -	Synethsis phase
        -	Chromosome replication
G2
        -	Check point at G2/M
M
        -	Mitosis

Question 3

Explain how cyclins and cyclin-dependent kinases regulate the cell cycle.

Answer 3

• Certain cyclins expressed at different cell cycle

* Certain kinases activated by cyclin and will activate\inhibite cell cycle proteins

Question 4

List the key cellular types involved in wound healing.

Answer 4

• Leukocytes, Neutrophils, macrophages

* Fibroblasts

Question 5

List and state the rolls of these extracellular matrix elements: collagen types I and IV, fibronectin, laminin, and proteoglycans.

Answer 5

1. Collagen
   
   • I: Most abundant in skin & bone
   • II: Cartaliage & vitrous humor
   • IV: Basement membrane
2. Fibronectin: Binds many extracellular membrane components
3. Lamin: Cell attachment
4. Proteoglycans: Electrostatic charge of basement membrane

Question 6

Explain the stages of scar formation from initial wound to collagen maturation.

Answer 6

1. Inflammation
   - Initial injury
   - Removal of dead & ijured tissue
   -
2. Granulation Tissue
   - Proliferation & migration of parenchymal & connective tissue
   - Synthesis of ECM proteins & collagen
3. Wound Contraction
   - Tissue remodeling
   - Contraction
   - Wound strength

Question 7

List the functions served by macrophages, fibroblasts and endothelial cells in wound healing.

Answer 7

Macrophages

- Wound decontamination
- Wound debridement
- Autocrine & paracrine growth factor release
- Has to transition from circulating macrophage to tissue macrophage

Fibroblasts

- Granulation tissue formation
- Provisional matrix lysis and ECM remodeling
- Connective tissue formation
- Transition from cell rich granuloma to cell-poor scar
- Tissue contratction
- Growth factor release

Endothelial cells

- Re-epithelialization
- Provesional ECM production
- Reestablish barrier function
- Protease relase to dissect clots

Question 8

Distinguish wound healing by primary vs. secondary intention.

Answer 8

Primary Inetention
-	Wound closure
-	Scab
-	Blood clot
-	Edges are approximated
Secondary Inetention
-	Wound granulation
-	Wound contraction

Question 9

Describe granulation tissue at the gross and histological levels.

Answer 9

• Collagen deposistion
• Dense cscars can form
• Woven appearance
• Fibroblast

Question 10

List six systemic and four local factors that influence the success of wound healing.

Answer 10

Systemic

1. Nutrion
2. Metabilic status
3. Circulation
4. Hormones
5. Genetics
6. Medical treatment (steroids)

Local

1. Type of infection
2. Foreign bodies
3. Mechanical factors
4. Size, location & type of wound