Tissue Repair (Ch 4)

Question 1

EDS

Answer 1

• defect in collagen synthesis or structure
• 9 known defects
• type IV is a defect in type III collagen

Question 2

Osteogenesis imperfecta

Answer 2

• defect in collagen type I

Question 3

marfan

Answer 3

defect in fibrillin gene –> laxity of tissues (long, lanky frame; lens subluxation; aortic aneurysm)

Question 4

type 1 collagen

Answer 4

• MC type of collagen
• has high tensile strength
• found in bone, skin, tendon, most organs
• OI = defect in collagen type I
• in remodeling phase of wound healing (1 week - 6 months): type III collagen replaced by type I collagen –> increases tensile strength of tissue
• delayed wound healing in zinc deficiency
• a keloid is composed of masses of disorganized type I and III collagen.

Question 5

Type II collagen

Answer 5

• found in cartilage and vitreous humor

- “here’s T2 looking at You”

Question 6

Type III collagen

Answer 6

• found in granulation tissue, embryonic tissue, uterus, keloids, blood vessels, stomach
• pliable
• in proliferative stage of wound healing (day 3 - weeks after wound): deposition of granulation tissue and type III collagen, angiogenesis, epithelial cell proliferation, dissolution of clot, wound contraction (mediated by myofibroblasts)

Question 7

type IV collagen

Answer 7

found in BM

- goodpastures syndrome = antibodies against alpha3 subunit of noncollagenous

Question 8

Collagen synthesis

Answer 8

• hydroxylation of collagen mediated by Vit C
• cross-linking performed by lysol oxidase
• copper = required cofactor

Question 9

Basement Membrane

Answer 9

• have a net negative charge bc albumin is (-)
• composition: type IV collagen, proteoglycans (heparin sulfate), laminin, fibronectin, entactin
• loss of negative charge (proteoglycan) of renal glomerular BM –> proteinuria (nephrotic syndrome)

Question 10

PDGF

Answer 10

• secreted by activated platelets and macrophages
• induces vascular remodeling and SM cell migration
• stimulates fibroblast growth for collagen synthesis

Question 11

FGF

Answer 11

stimulates angiogenesis

Question 12

EGF

Answer 12

stimulates cell growth via tyrosine kinase (ex, EGFR/ErbB1)

Question 13

TGF-β

Answer 13

angiogenesis, fibrosis

Question 14

metalloproteinases

Answer 14

tissue remodeling

Question 15

VEGF

Answer 15

simulates angiogenesis