wound healing (W11)

Question 1

3 classifications of cells in terms of regeneration?

Answer 1

labile cells - divides in homeostasis, rapid regeneration
stable cells - don’t divide in homeostasis, regenerate after injury
permanent cells - unable to regenerate

Question 2

stable cells examples? (regeneration)

Answer 2

liver, kidney

Question 3

permanent cells examples? (regeneration)

Answer 3

neurons, cardiac myocytes

Question 4

what does unbalanced growth of cells lead to

Answer 4

neoplasia

Question 5

regenerative signals after cell injury?

Answer 5

soluble growth factors

Question 6

soluble growth factors types and explanations

Answer 6

paracrine - acts on neighbouring cells
autocrine - act on same cell signals are released
endocrine - enters blood stream and acts on other cells

Question 7

how do soluble growth factors act on cells

Answer 7

bind to receptors triggering intracellular cascade (via phosphorylation) ending up causing change in gene transcription to change behaviour

Question 8

how do soluble growth factors act on cells

Answer 8

bind to receptors triggering intracellular cascade (via phosphorylation) ending up causing change in gene transcription to change behaviour

Question 9

what are cell-matrix interactions mediated by

Answer 9

integrins (cell surface receptors that bind to the extracellular matrix)

Question 10

how does healing by scarring occur

Answer 10

bleeding
clot formation
acute -> chronic inflammation
fibroblast infiltration
angiogenesis (new blood vessels)
scar maturation

Question 11

epidermal cells vs dermis cells? (regeneration)

Answer 11

epidermal cells - labile
dermis - some permanent, cannot be completely replaced

Question 12

what happens if there is significant injury to the dermis

Answer 12

heal by scarring

Question 13

what will epidermal cells almost instantly do after damage?

Answer 13

no longer in contact with epidermal cells, will proliferate to replace the gap

Question 14

granulation tissue?

Answer 14

tissue underneath a scab in the first few days - early new vessels, acute inflammation. clot is beginning to be removed.

Question 15

what is the name for blood vessel formation in adulthood?

Answer 15

angiogenesis

Question 16

type of angiogenesis where residual blood vessels sprout off and form new ones in the area vessels were lost?

Answer 16

sprouting

Question 17

what do macrophages/neutrophils produce to help with blood vessel growth

Answer 17

vascular endothelial growth factor (VEGF)
nitric oxide (loosens connections between endothelial cells)
MMP (matrix proteases)

Question 18

MMP role in angiogenesis?

Answer 18

locally degrade basement membrane around outside of blood vessel to allow sprouts

Question 19

what receptors do new endothelial cells in angiogenesis and why

Answer 19

VEGF receptors - allows them to migrate towards source of injury

Question 20

what cells wrap around the outside of a blood vessel and produce the basement membrane? what do they respond to?

Answer 20

pericytes
PDGF - platelet derived growth factor

Question 21

resident mesenchymal cells in the dermis? what do they produce

Answer 21

fibroblasts
connective tissue

Question 22

growth factors influencing fibroblasts?

Answer 22

TGF-beta produces fibroblast migration, proliferation, ECM production/degradation

PDGF produces proliferation

Question 23

types of collagen and features?

Answer 23

type 1 & 3 - thick, scarring, structural (hold things in place)
type 4 - basement membrane, looser

Question 24

non collagen components of ECM examples?

Answer 24

elastin
proteoglycans
glycoproteins

Question 25

what causes degradation of granulation tissue? What are they regulated by?

Answer 25

matrix metalloproteinases (MMPs)
regulated by TIMPs

Question 26

what mediates long term scar maturation and degradation

Answer 26

matrix metalloproteinases (MMPs)