Tissue Healing/Repair Flashcards Preview

Foundations Test 4 > Tissue Healing/Repair > Flashcards

Flashcards in Tissue Healing/Repair Deck (24):
1

Healing

Outcome of inflammation - regeneration or scarring

2

Cell growth in scarring vs. regneration

Regen - tissue's own cells divide

Scar- fibroblasts and vascular endothelial cells divide

3

Liable cells

Continuously dividing
Short G0
Epithelial cells and hematopoietic cells

4

Stable cells

Low rate of cell division
Long G0
Re-enter cell cycle only under certain circumstances (healing)
Vascular endothelial cells, parenchymal cells of organs, mesenchymal cells

5

Permanent cells

Left cell cycle forever...will never undergo mitosis again
Neurons of CNS, cardiac muscle, skeletal muscle

6

3 conditions for healing by regeneration

Tissue composed of labile or stable cells
Area of injury has surviving cells capable of undergoing cell division
Connective tissue framework intact

7

Healing by scarring conditions

Tissue consists of permanent cells and/or no surviving cells remain and/or connective tissue framework is destroyed/disrupted

8

Growth factors

May promote cell proliferation by recruiting G0 cells into cell cycle...may inhibit cell proliferation...may influence other cell function

9

Epidermal growht factor family

EGF and TNF-alpha

10

EGF

Produced by several cells, including macrophages
Mitogenic for epithelial cells, hepatocytes and fibroblasts
Binds to ERB B1

11

TGF-alpha

Almost same to EGF, also binds to ERB B1

12

PDGF

Stored in alpha granules of platelets
Released when platelets activated
Also produced by macrophages, edothelial cells, smooth muscle, and some tumor cells
Mitogenic and chemitactic for fibroblasts, smooth muscle cells, and monocytes

13

FGF

Acidic and basic types
Produced by activated macrophages
Chemotactic and mitogenic for fibroblasts and endothelial cells
Induce angiogenesis

14

TGF-B

Produced by platelets, endothelial cells, lymphocytes, and activated macrophages
Generally mitogenic for fibroblasts but can inhibit grwoth of epithelial cells
Stimulates fibroblast chemotaxis, and stimulates production of collagen and fibronection (important for scars)

15

Fibrogenic cytokines

IL-1 and TNF

Mitogenic and chemotactic for fibroblasts
Stimulate collagen production by fibroblasts
Important in scar formation

16

Direct binding of what is critical for regeneration and scar formation?

Cell to the ECM

17

4 components of repair by fibrosis

Angiogenesis/neovascularization
Migration and proliferation of fibroblasts
Deposition of ECM components, including collagen
Organization of the fibrous tissue into a mature scar (remodeling)

18

In fibrosis, 24 hours after tissue injury

Fibroblasts and vascular endothelial cells proliferate

19

Granulation tissue

Formed by proliferation of fibroblasts and vascular endothelial cells

20

2 important features of granulation tissue

Angiogenesis and fibroblast proliferation

21

Angiogenesis - granulation tissue

New vessels originate from other blood vessels in the area
New vessels have leaky interendothelial junctions allowing exudate to form (tissue is edematous)
Need FGF and VEGF in order to grow

22

Fibroblast proliferation - granulation tissue

Triggered by EGF, TGF-B, PDGF, and others
TGF-B stimulates newly created fibroblasts to secrete collagen

23

Weeks to months after, how is granulation tissue turned into a scar?

Amount of collagen and other ECM proteins increases
Number of fibroblasts and other other vascularity decreases
Fully mature scare is practically avascular and has dense collagen

24

Healing of a surgical incision

Scalpel blade injures a number of epidermal cells and underlying connective tissue
Space fills with clotted blood
Neutrophils appear (24 hours)
By day 3, replaced with macrophages
At day 3, granulation tissue begins to form because of growht factors from platelets, macrophages, and endothelial cells...TGF-B stimulates production of collagen and other ECM proteins
Growth factors induce basal cells of the epidermis to regenerate
By day 5, granulation tissue has filled incisional space
During second week, collagen accumulates while leukocytes, edema, and increased vascularity begin to disappear
By then end of the first month, scar is formed and epidermis fully regenerated

It is then complete