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Flashcards in 14 Wound Healing Deck (98):
1

what are the phases of wound healing?

inflammation, proliferation, remodeling

2

how long dose inflammation last?

1-10d

3

what happens during inflammation?

pmns, macrophages, epithelialization

4

how fast does epithelialization work?

1-2mm/d

5

how long does proliferation last?

5d-3weeks

6

what happens during proliferation?

fibroblasts, collagen deposition, neovascularization, granulation tissue formation, type III collagen replaced w type I

7

how long does remodeling last?

3w to 1 yr

8

what happens to vascularity during remodeling?

decreased vascularity

9

what happens during remodeling?

collagen cross-linking occurs

10

does the amount of collagen increase or stay the same during remodeling?

net amount doesn't change but significant production and degradation occur

11

how fast do peripheral nerves regenerate?

1mm/d

12

what is the order of cell arrival in a wound?

platelets, PMNs, macrophages, lymphocytes, fibroblasts

13

illustrate timeline of phases of wound healing with dominant cell types and major physiologic events

http://cl.ly/image/1R0L3o3L3a0Y

14

what do macrophages do?

essential for wound healing: release growth factors, cytokines, etc.

15

what does fibronectin do?

chemotactic for macrophages; anchors fibroblasts

16

what do fibroblasts do?

replace fibronectin-fibrin with collagen

17

list the prominent cell type by day.

day 0-2: PMNs
days 3-4: macrophages
days 5 and on: fibroblasts

18

what is a platelet plug consisted of?

platelets and fibrin

19

what does a provisional matrix consist of?

platelets, fibrin, fibronectin

20

what is accelerated wound healing?

reopening a wound results in quicker healing the 2nd time (as healing cells are already present there)

21

what is the most important factor in healing open wounds (secondary intention)

epithelial integrity

22

what happens to epithelial cells on the skin near open wounds?

epithelial cells migrate from hair follicles (#1 site), wound edges, and sweat glands

23

what is epithelial integrity dependent on?

granulation tissue in wound

24

what happens to unepithelialized wounds?

leak serum, protein, promote bacteria

25

what is the most important factor in healing closed incisions (primary intention)?

tensile strength

26

what does tensile strength depend on?

collagen deposition and cross-linking of collagen

27

what is the strength layer of bowel?

submucosa

28

when is the weakest time point for small bowel anastomosis?

3-5d

29

how do myofibroblasts communicate?

gap junctions

30

what are myofibroblasts called in the smooth muscle cell?

fibroblast

31

what do myofibroblasts do?

involved in wound contraction and healing by secondary intention

32

what has better wound contraction: perineum or leg?

perineum

33

what is the most common type of collagen?

I

34

what is the primary collagen in a healed wound?

I

35

what type of tissue is type I collagen?

skin, bone, tendons

36

what type of tissue is type II collagen

cartilage

37

what collagen type is increased in a healing wound?

III

38

what type of collagen is in blood vessels and skin?

III

39

what type of collagen makes up basement membranes?

IV

40

what type of collagen is widespread?

V

41

what type of collagen is particularly found in the cornea?

V

42

what is what is required for hydroxylation?

alpha-ketoglutarate, vitamin C, oxygen, and iron.

43

what is the enzyme that mediates hydroxylation?

prolyl hydroxylase

44

why is hydroxylation needed in wound healing?

cross-links proline residues in collagen

45

which amino acid crosslinks in collagen? how often is it in the protein?

proline. every 3rd amino acid.

46

what does proline cross linking do?

improves wound tensile strength

47

what is scruvy?

vitamin C deficiency

48

can tensile strength equal to pre-wound?

no. only 80%

49

which types of collagen are predominant at which periods of wound healing?

days 1-2: type III
days 3-4: type I collagen

50

when is type III replaced by type I collagen?

by 3 weeks of wound healing

51

when does a wound reach max tensile strength?

8 weeks

52

when is maximum collagen accumulation reached? what happens after that?

2-3 weeks. afterwards, continued cross-linking improves strength

53

what does d-penicillamine do?

inhibits collagen cross-linking

54

what are the essentials for wound healing?

moist environment, oxygen delivery, avoid edema, remove necrotic tissue

55

how is oxygen delivery to wound maximized?

optimize fluids, no smoking, pain control, arterial revascularization, supplemental O2

56

what should transcutaneous oxygen measurement be to maximize wound healing?

TCOM > 25mmhg

57

what are impediments to wound healing?

bacteria, devitalized tissue, foreign bodies, cytotoxic drugs, diabetes, low albumin, steroids, wound ischemia

58

how is bacteria an impediment to wound healing?

decreases oxygen content, collagen lysis, prolonged inflammation

59

how are devitalized tissue and foreign bodies impediments to wound healing?

retards granulation tissue formation

60

which cytotoxic drugs are impediments to wound healing and when do they impair wound healing?

5FU, methotrexate, cyclosporine, FK-506, etc. impair wound healing in 1st 14 days after injury

61

how does diabetes contribute to poor wound healing?

impedes early phase inflammation response (hyperglycemia causes poor leukocyte chemotaxis)

62

how low does albumin need to go before it becomes a risk factor for poor wound healing?

<3.0

63

how much bacteria is required before it impedes wound healing?

>10^5/cm^2

64

how do steroids impede wound healing?

inhibit macrophages, PMNs, collagen synthesis by fibroblasts. decreases wound tensile strength as well

65

what counteracts effects of steroids on wound healing?

vitamin A 25,000 IU qd

66

what causes wound ischemia?

hypoxia. caused by fibrosis, pressure (sacral decub, pressure sores), poor arterial inflow (atherosclerosis), poor venous outflow (venous stasis), smoking, radiation, edema, vasculitis

67

what diseases are associated with poor wound healing?

osteogenesis imperfecta
ehlers-danlos syndrome
marfan's' syndrome
epidermolysis bullosa
scurvy
pyoderma gangrenosum

68

how is osteogenesis imperfecta associated with abnormal wound healing?

type I collagen defect.

69

how is ehlers-danlos syndrome associated with abnormal wound healing?

10 types identified, all collagen disorders

70

how is marfan's syndrome associated with abnormal wound healing?

fibrillin defect (connective tissue protein)

71

how is epidermolysis bullosa associated with abnormal wound healing?

excessive fibroblasts

72

what is the treatment for epidermolysis bullosa?

phenytoin

73

how where do diabetic foot ulcers occur?

usually at charcot's joint secondary to neuropathy, also toes

74

what is charcot's joint?

2nd MTP join

75

what causes leg ulcers?

90% due to venous insufficiency

76

what is the treatment for leg ulcers?

unna boot (elastic wrap)

77

what do scars contain?

lots of proteoglycans, hyaluronic acid, water

78

when do you do scar revisions?

wait for one year to allow maturation; may improve with age

79

do infants scar?

heal with little or no scarring

80

does cartilage contain blood vessels? how do they get nutrients and O2?

no. get nutrients and o2 by diffusion

81

does denervation have any effect on wound healing?

no

82

does chemo have any effect on wound healing?

not after 14 days

83

who gets keloids?

it's autosomal dominant; dark skinned people

84

what are keloids?

collagen goes beyond original scar

85

what is treatment for keloid?

intra-lesion steroid injection; silicone, pressure garments, XRT

86

who gets hypertrophic scar tissue?

dark skinned

87

where does hypertrophic scar tissue form?

flexor surfaces of upper torso

88

how is hypertrophic scar tissue different from keloid?

in hypertrophic scar tissue, collagen stays within confines of original scar

89

how do people get hypertrophic scar tissue?

often occurs in burns or wounds that take a long time to heal

90

what is the treatment for hypertrophic scar tissue?

steroid injection, silicone, pressure garments

91

what are the different platelet granules?

alpha and dense granules

92

what are the alpha granules?

platelet factor 4, beta-thrombomodulin, PDGF, TGF-beta

93

what does platelet factor 4 do?

aggregation

94

what does beta-thrombomodulin do?

binds thrombin

95

what does PDGF do?

chemoattractant

96

what does TGF-beta do?

transforming growth factor beta modulates activity of platelet factor 4, beta-thrombomodulin, and PDGF

97

what do dense granules contain?

adenosine, serotonin, calcium

98

what are the paltelet aggregation factors?

TXA2, thrombin, platelet factor 4