Exam 1: Ch 4 Flashcards Preview

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Flashcards in Exam 1: Ch 4 Deck (46):
1

proliferation

increase in cell number by mitotic division

endothelial cells & fibroblasts proliferate during tissue repair

driven by growth factos

2

differentiation

when stem cells specialize in structure & function

multiple orderly steps driven by expression of a tissue-specific set of genes

3

many tissues retain ______ cells that are....

progenitor cells

able to replace cells for that tissue only

4

interphase

G1: RNA & protein synthesis

S: DNA replication

G2: protein synthesis

5

mitosis

2 cells form from 1

6

cell cycle checkpoints

allow opportunity for repair

no progression from G1 --> S if DNA is damaged

no progression from G2 ---> M if DNA wasn't duplicated

7

cell cycle regulation

cyclins control cell cycle by activating protein kinases (CDK)

CDKs phosphorylate target proteins to activate them

causes progression through cell cycle

progression through specific checkpoints controlled by specific cyclins

8

proliferative capacity

labile cells like intestinal endothelium cycle continuously

other cells become stable and stop cycling

9

stable cells and G0

stop cycling = G0

stable cells can re-enter cycle with proper stimulation

some stable cells stop cycling permanently -- nerve, skeletal/cardiac muscle

10

stem cells

cells that remain incompletely differentiated throughout life

divide to: replace cells that died from apoptosis, or to produce another stem cell

11

properties of stem cells

self renewal: one cell form each mitotic division remains a stem cell (undifferentiated)

asymmetric replication: 2 cells from mitotic division are not identical -- one differentiates, the other does not

12

types of stem cell potency

stem cells have different differentiation potential

totipotent

pleuripotent

multipotent

unipotent

13

totipotent stem cells

can produce all tissue types and placenta

cells generated by the first few divisions of fertilized ovum

14

pleuripotent stem cells

can produce all embryonic tissue types

15

multipotent stem cells

can produce a few related cell types

ex. hemocytoblasts

16

unipotent stem cells

can produce 1 cell type only

17

embryonic vs. adult (somatic) stem cells

embryonic are pleuripotent

adult may have less capacity

18

growth factos

small hormone-like proteins that are chemical triggers for cellular proliferation

contribute to tissue regeneration & wound healing

19

how are growth factors named

for tissue of origin

EGF: epidermal growth factor

TGF: transforming growth factor

VEGF: vascular endothelial cell growth factor

20

mechanism of growth factors

bind to surface receptors, activate 2nd messenger systems, increase expression of specific genes --> cellular division

21

ECM includes

basement membrane (borders epithelial tissue)

interstitial matrix (between cells of connective tissue)

22

ECM contains

protein fibers: collagen & elastin

water-hydrated gels: proteoglycans & hyaluronic acid

adhesion glycoproteins: fibronectin & laminin

23

cells have integrins that...

bind to adhesion molecules

24

fibroblasts produce...

collagen fibers

25

functions of ECM

provides turgor to soft tissue (structure of proteins is different between old/young skin b/c of H2O loss)

regulates cell movement & differentiation

scaffold for tissue renewal after injury

26

primary goal of healing by conn. tissue repair

fill gap created by injury and restore structure of neighboring tissues

27

regeneration

restoration of injured tissue to a normal state

28

scar formation

replacement of injured tissue with fibrous connective tissue

29

phases of tissue repair

angiogenesis & ingrowth of granulation tissue

emigration of fibroblasts and deposition of ECM

maturation and remodeling of fibrous tissue

30

angiogenesis

phase 1 of tissue repair

growth of new blood vessels stimulated by VEGF & FGF

new vessels are initially leaky --> wound edema persisting after inflammation

31

ingrowth of granulation tissue

phase 1 of tissue repair

granulation tissue: conn. tissue that fills injured area while necrotic debris is removed

requires new blood vessels

32

emigration of fibroblasts and deposition of ECM

fibroblasts migrate to wound and proliferate

deposit ECM including collagen

stimulated by FGF & TGF-beta

33

maturation and remodeling of fibrous tissue

transition from granulation tissue to scar tissue

ECM remodeled by metaloproteases

34

healing of skin wounds

involves both epithelium & conn. tissue

primary intent

secondary intent

35

primary intent

sutured surgical incision -- only for clean wounds

36

secondary intent

wound left open and irrigated

for larger wounds with tissue loss & contaminated wounds

37

phases of wound healing

inflammatory

proliferative

remodeling

38

inflammatory phase (phase 1 of wound healing)

starts at time of injury

blood clotting and vasoconstriction stop bleeding

vessels dilate to bring inflammatory cells to the wound

neutrophils/macrophages phagocitize bacteria and release growth factors

GF stimulate angiogenesis & attract fibroblasts

39

proliferative phase (phase 2 of wound healing)

starts 2-3 days post-injury

fibroblasts secrete collagen and produce GF

endothelial cells proliferate and migrate to close wound edges

granulation tissue forms

collagen synthesis continues

40

remodeling phase (phase 3 of wound healing)

starts at ~3 weeks post-injury

collagen is remodeled and epithelium reestablished

the wound contracts -- limits scar size but can also limit joint movement

41

keloid

excess scar tissue production

42

factors affecting wound healing

nutritional status

blood flow

impaired inflammatory response

infection, wound separation, foreign bodies

43

nutritional status

wound healing requires adquate protein, carbohydrates, & vitamins

44

blood flow for wound healing

O2 needed for collagen synthesis and phagocytosis

ischemic tissue heals slowly

45

impaired inflammatory response

disorders that impair action of phagocytes slow wound healing

46

infection, wound separation, foreign bodies

uncontaminated wounds with no foreign bodies and approximated edges heal the fastest