#4 healing/repair

Question 1

regeneration

Answer 1

repair process in which injured or dead cells are replaced by replicating cells of the same type. Connective tissue/extracellular matrix of the organ is intact

Question 2

replacement

Answer 2

connective tissue replaced the injured or dead cells replacing it with fibrous tissue (scar). Happens if either the connective tissue framework was destroyed or the parenchymal cells cannot regenerate.

Question 3

labile cells

Answer 3

continuously divide. Lost cells replaced by
maturation from stem cells or proliferation of mature cells. (epithelium of skin and mucous membranes, and hematopoietic cells)

Question 4

stable cells

Answer 4

low level of replication but divide rapidly when stimulated. In G0 (quinescence phase) of cell cycle. Examples- liver, kidney, pancreas, smooth muscle cells, fibroblasts.

Question 5

permanent cells

Answer 5

non-dividing, terminally differentiated. brain and heart and sort of skeletal muscle

Question 6

process of replacement by connective tissue

Answer 6

1. angiogenesis- VEGF (vascular endothelial growth factor)
2. migration and proliferation of fibroblasts- TGF-B, PDGF(platelet derived GF), and FGF (fibroblast GF)
3. formation and deposition of extracellular matrix (by fibroblasts)
4. maturation and organization of the fibrous tissue elements.

Question 7

granulation tissue

Answer 7

the tissue that fills in defects when non-regenerative cells and/or connective tissue framework is destroyed. It consist of proliferating fibroblasts and new blood vessels. It appears red and edematous to the naked eye. It is only present during healing

Question 8

organization

Answer 8

the process of transforming granulation tissue into dense scar tissue. connective tissue elements mature and blood vessels become less prominent.

Question 9

healing by first intention (primary union)

Answer 9

using sutures to speed up heeling. Wound is usually clean, limited in the amount of destroyed tissue. Epithelial regeneration principle mechanism of repair.

Question 10

healing by second intention (secondary union)

Answer 10

Same process as internal organ healing.
Large skin wound
Extensive destruction, contaminated, infected
Edges are not approximated
Larger clot, more intense inflammation
Wound granulates in without closing gap with sutures
Process of healing same but takes longer because of the size of the defect
Wound contraction by myofibroblasts

Question 11

hypertrophic scar

Answer 11

excess production of scar tissue localized to the wound (may regress)

Question 12

keloid

Answer 12

exuberant amount of collagen, grows beyond wound boundaries. May be hereditary more common in african americans.

Question 13

what initiates the repair process?

Answer 13

inflammation

Question 14

2 requirements for regeneration

Answer 14

1. connective tissue intact

2. cells are capable of dividing

Question 15

composition of ECM

Answer 15

fibrous structural proteins (collagens, elastins)
water hydrated gels (proteoglycans, hyaluronan)
Adhesive glycoproteins

Question 16

ECM

Answer 16

network of interstitital proteins

2 forms: interstitial matrix and basment membrane

Question 17

pros and cons of scar tissue

Answer 17

Con- Fibrous tissue cannot perform function of lost parenchymal cells
Pro- Scar usually provides enough structural stability for injured tissue to continue function

Question 18

VEGF

Answer 18

Family of growth factors
Promote angiogenesis
Increase vascular permeability
Stimulate endothelial cell migration, proliferation
Expressed at low levels in most adult tissues
Expressed at higher levels in a few sites
(Podocytes in glomerulus, pigment epithelium of retina)
Hypoxia = important inducer
Mutations = defective angiogenesis and vasculogenesis

Question 19

Fibrosis

Answer 19

excessive deposition of collagen and other ECM components in a tissue

Question 20

important nutrients for wound healing

Answer 20

vitamin C, Zinc, Copper

Question 21

Dehiscence

Answer 21

wound breaks open

Question 22

contracture

Answer 22

get lots of myofibroblast to pull it together and shrink the size of the injury