wound healing

Question 1

basic principles (regeneration)

Answer 1

healing is initiated when inflammation begins

occurs via a combination of regeneration and repair

Question 2

regeneration

Answer 2

replacement of damaged tissue with native tissue, dependent on regenerative capacity of tissue

Question 3

types of cells (regeneration)

Answer 3

3 types based on regenerative capacity

labile, stable, permanent

Question 4

labile tissues (regeneration)

Answer 4

possess stem cells that continuously cycle to regenerate the tissue

small and large bowel, skin, bone marrow

Question 5

stable tissues (regeneration)

Answer 5

compromised of cells that are quiescent (Go) but can reenter the cell cycle to regenerate tissue when necessary

regeneration of liver by compensatory hyperplasia after partial resection. each hepatocyte produces additional cells and then reenters quiescence

Question 6

permanent tissues (regeneration)

Answer 6

lack significant regenerative potential

myocardium, skeletal muscle and neurons

Question 7

repair

Answer 7

occurs when damaged tissue with fibrous scar

regenerative stem ells are lost or a tissue lacks regenerative capacity

Question 8

initial phase of repair

Answer 8

granulation tissue formation

consists of fibroblasts (deposit type III collagen) capillaries (provide nutrients) and myofibroblasts (contract wound)

Question 9

result of repair

Answer 9

scar formation, type III collagen is replaced with type I collagen

Question 10

type III collagen

Answer 10

pliable and present in granulation tissue, embryonic tissue, uterus and keloids

Question 11

type I collagen

Answer 11

high tensile strength and is present in skin, bone, tendons, and most organs

Question 12

collagenase

Answer 12

removes type III collagen and requires zinc as a co-factor

Question 13

mechanism and regeneration and repair

Answer 13

mediated by paracrine signaling via growth factors

interaction of growth factors with receptors results in gene expression and cellular growth

Question 14

mediatitor examples

Answer 14

TGF-a epithelial and fibroblast growth factor

TGF-B important fibroblast growth factor; also inhibits inflammation

platelet-derived growth factor-growth factor for endothelium, smooth muscle, and fibroblast

fibroblast growth factor-important for angiogenesis; also mediates skeletal development

vascular endothelial growth factor (VEGF)-important for angiogenesis

Question 15

cutaneous wound healing

Answer 15

occurs via primary or secondary intention

Question 16

primary intention

Answer 16

wound edges are brought together, leads to minimal scar formation

Question 17

secondary intention

Answer 17

edges are not approximated. granulation tissue fills defect; myofibroblasts then contract the wound, forming a scar.

Question 18

delay in would healing occurs in:

Answer 18

infection
vitamin C, copper, or zinc deficiency

foreign body, ischemia, diabetes and malnutrition

Question 19

dehiscence

Answer 19

rupture of a wound; most commonly seen after abdominal surgery

Question 20

hypertrophic scar

Answer 20

excess production of scar tissue that is localzied to the wound

Question 21

keloid

Answer 21

excess production of scar tissue that is out of proportion to the wound

excess type III collagen
genetic predisposition (AA)
affects earlobes, faces, and upper extremities