Wound Healing

Question 1

describe labile cells

Answer 1

proliferate throughout life (epithelia, blood cells)

Question 2

describe what is seen in the image and what kind of cells they are

Answer 2

proliferating endometrium = labile cells

Question 3

describe stable cells

Answer 3

low normal replication rate, unless stimulated

considered to be on G0 but recruited to G1

Question 4

describe what is seen in the image and describe what kind cells they are

Answer 4

renal tubular cells = stable cells

Question 5

describe permanent cells

Answer 5

unable to divide; have left cell cycle

ex: neurons, cardiac myocytes

Question 6

describe what is seen in the image and describe what kind of cells they are

Answer 6

Question 7

give an example of atypical regeneration

Answer 7

blue = scar tissue

Question 8

describe fibronectins

Answer 8

• seen in cell surfaces, basement membranes and pericellular matrices
• produced by fibroblasts, endothelial cells and monocytes
• in wound healing they facilitate migration of new epithelium (glue-like), are chemotactic for monocytes and are chemotactic for fibroblasts
• stimulate endothelial cell migration and organization

Question 9

describe collagenization and wound strength

Answer 9

• in injury is severe or persistent with damage of both parenchymal cells and stromal framework –> regeneration is not enough
• initial replacement by granulation tissue: pink, soft, painless (3-5 days), capillaries, fibroblasts, inflammatory cells in a soft ECM mesh
  
  • serves as scaffold for scar

Question 10

list the steps in repair

Answer 10

• angiogenesis: new vessels
  
  • chem. mediators: VEGF and b-FGF
• fibrosis: fibroblast proliferation and production of ECM
  
  • growth factors
• maturation and organization (remodeling): of collagen and other ECM
  
  • internal debridement of wound

Question 11

describe the initial phase of repair

Answer 11

• initial steps:
  
  • cross-linking of fibrin
  • removal of debris
  • chemotaxis

Question 12

describe the late stages of repair

Answer 12

• resolution with:
  
  • removal of clot
  • new temporary ECM (type III collagen)
  • final ECM (type I collagen)

Question 13

describe wound strength

Answer 13

• 70-80% of tensile strength in 3 months
• cicatrization: replacement of type III collagen by type I

Question 14

describe the repair of skin wounds

Answer 14

Question 15

describe keloids

Answer 15

• excessive scar
• red, raised and firm
• irregular, excessive collagen in dermis

Question 16

describe what is seen in the image

Answer 16

Question 17

describe primary vs secondary repair

Answer 17

• primary repair or by first intention = edges of wound in apposition because it is superficial or sutured
• secondary repair or by second intention = increased tissue loss, lots of granulation tissue, larger scar