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Surgical Biology > Wound Healing > Flashcards

Wound Healing Flashcards

1
Q

T/F: Clean-contaminated wounds are open, acute, accidental, or surgical wounds in which there has been a major break in sterile technique.

A

False; Clean-contaminated wounds are surgical wounds in which the respiratory, alimentary, or urogenital tracts are entered under controlled conditions without unusual contamination, whereas contaminated wounds are open, acute, accidental, or surgical wounds in which there has been a major break in sterile technique.

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2
Q

T/F: Dirty or infected wounds are those that are old, have devitalized tissue, or have gross contamination with foreign debris.

A

True

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3
Q

Clean, clean-contaminated, and contaminated wounds by definition contain less than ________ bacteria per gram of tissue.

A

1 × 10^5

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4
Q

A type of injury occurring when the body part is subjected to a high degree of force between two heavy objects.

A

Crush

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5
Q

A type of injury involving a blow to the skin in which blood vessels are damaged or ruptured.

A

Contusion

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6
Q

A type of injury involving damage to the skin epidermis and portions of the dermis by blunt trauma or shearing forces.

A

Abrasion

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7
Q

A type of injury involving loss of skin or tissue characterized by tearing of the tissue from its attachments.

A

Avulsion

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8
Q

A type of injury involving a wound created by a sharp object that has minimal adjacent tissue damage.

A

Incision

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9
Q

A type of injury involving an irregular wound created by tearing of tissue. Skin and underlying tissue damage can be variable.

A

Laceration

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10
Q

A type of injury involving a penetrating injury to the skin resulting in minimal skin damage and variable underlying tissue damage. Contamination with dirt, bacteria, and hair is common.

A

Puncture

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11
Q

Immediate suture closure without tension of a clean or clean-contaminated wound converted to clean wound.

A

Primary closure

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12
Q

Which of the following statements defines secondary closure of a wound?

  1. Immediate suture closure without tension
  2. Performed 2-5 days after injury; tissue débridement and wound lavage before closure
  3. Performed at least 5 days after injury; granulation tissue and epithelialized skin edges excised at the time of closure
  4. Healing by granulation tissue, wound contracture, and epithelialization
A

Secondary closure = Performed at least 5 days after injury; granulation tissue and epithelialized skin edges excised at the time of closure

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13
Q

What closure would you select for a clean or clean-contaminated wound converted to clean wound?

A

Primary closure; immediate suture closure without tension

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14
Q

What closure would you select for a clean-contaminated or contaminated wound with questionable tissue viability, edema, skin tension?

A

Delayed primary closure performed 2-5 days after injury; tissue débridement and wound lavage before closure

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15
Q

What closure would you select for a contaminated or infected wound?

A

Secondary closure performed at least 5 days after injury; granulation tissue and epithelialized skin edges excised at the time of closure

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16
Q

What closure would you select for a large skin defect and/or extensive tissue devitalization?

A

Second intention healing Wound tissue is unsuitable for closure; Healing by granulation tissue, wound contracture, and epithelialization

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17
Q

This phase in wound healing involves hemostasis and inflammation, is a very metabolically active period lasting for several days, during which wound healing is jump started.

A

Inflammatory or lag phase

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18
Q

Reflex vasoconstriction occurs by smooth muscle contraction mediated by release of _________ and _____________ from the injured vessels and platelet-derived __________. The response is transient, lasting only ___ to ___ _______, after which vasodilators such as _________, __________, and _______ _______ predominate, facilitating diapedesis of cells, fluid, and protein into the wound and extracellular space.

A

endothelin and thromboxane A2; serotonin; 5 to 10 minutes; prostacyclin, histamine, and nitric oxide

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19
Q

T/F: Hemostasis during the lag phase is ultimately achieved through compression of vessels by soft tissue swelling and formation of a fibrin-platelet plug within the wound defect.

A

True

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20
Q

The activated platelets within this fibrin plug amplify the early inflammatory phase of healing through the release of wound repair mediators, most importantly_______-______ ________ ______ and ________ _______ _______-_______, from their storage granules.

A

platelet-derived growth factor (PDGF); transforming growth factor beta (TGF-β)

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21
Q

________________ ______ are the first cell type to enter the wound in large numbers. They appear soon after injury, with numbers peaking on about day 2, and decline as debris is cleared from the injured site.

A

Polymorphonuclear cells (PMNs, neutrophils)

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22
Q

The principal degradative proteinases released by PMNs to remove damaged tissue include __________, neutrophil-specific __________ ________, and neutrophil ________.

A

cathepsin G; interstitial collagenase; elastase By 24 hours, circulating monocytes begin to enter the wound and differentiate into macrophages

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23
Q

By ______ after injury, circulating monocytes begin to enter the wound and differentiate into macrophages.

A

24 hours

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24
Q

What are the proteinases released by macrophages that aid in wound debridement?

A

elastase, collagenase, and plasminogen activator

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25
Q

T/F: Macrophages may be present for a period lasting from a few days to weeks, depending on wound characteristics. Their synthesis and release of tissue growth factors initiates the proliferative phase of the repair process, including angiogenesis, fibroplasia, and epithelialization.

A

True

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26
Q

T/F: Neutrophil and macrophage apoptosis occurs as the inflammatory phase subsides.

A

True

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27
Q

The _________ phase of acute tissue repair is active by the ____ day following injury. It is characterized by angiogenesis, fibrous and granulation tissue formation, collagen deposition, epithelialization, and wound _________.

A

proliferative; third; contraction

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28
Q

T/F: Decreased oxygen tension, high lactate levels, and low pH within the wound initiate the process of angiogenesis.

A

True

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29
Q

T/F: The endothelial cells at the tips of capillaries adjacent to the wound grow in response to cytokines released by platelets and macrophages at a rate of 1.0 to 2.0 mm per day.

A

False; The endothelial cells at the tips of capillaries adjacent to the wounded area are attracted to the area by fibronectin, found within the provisional matrix, and grow in response to cytokines released by platelets and macrophages at a rate of 0.4 to 1.0 mm per day.

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30
Q

T/F: Fibroblasts begin to arrive by the fifth day after injury.

A

False; Fibroblasts begin to arrive by the second day after injury, and by the fourth day they are the major cell type in the wound bed. Peak in fibroblast numbers is at 7 to 14 days after injury.

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31
Q

Multiple cytokines are involved in wound repair. Which one of the following cytokines induces the differentiation and maturation of hematopoietic stem cells?

  1. vascular endothelial growth factor (VEGF)
  2. interferon (IFN)
  3. colony-stimulating factor (CSF)
  4. tumor necrosis factor
A

colony-stimulating factor (CSF)

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32
Q

Fibroblast migration into the wound and their subsequent proliferation is largely regulated by ________, _________ and __________.

A

Platelet-derived growth factor (PDGF); Transforming growth factor-β (TGF-β); Basic fibroblast growth factor (bFGF)

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33
Q

T/F: Fibroblasts synthesize and release collagen; glycosaminoglycans, including hyaluronan (which facilitates cell migration); glycoproteins (fibronectin and laminin); and proteoglycans.

A

True

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34
Q

T/F: Fibroblasts secrete proteases, including MMPs, which digest the fibrin clot so that replacement with the new components can occur.

A

True

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35
Q

Collagen production begins slowly on the ___________ after wounding and reaches peak production within __________.

A

second or third day; 1 to 3 weeks

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36
Q

T/F: Wound fibroblasts produce type II collagen.

A

False; although wound fibroblasts produce type I collagen, which predominates in unwounded dermis, almost 30% to 40% of the collagen found in the acute wound will be type III (blood vessels).

Type I collagen = bone, tendon, skin (fibroblasts)
Type II collagen = cartilage
Type III collagen = blood vessels

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37
Q

T/F: Fibroblasts within the wound organize the collagen molecules into bundles, which are aligned perpendicular to the wound surface.

A

False; fibroblasts within the wound organize the collagen molecules into fibers and then into bundles, which are aligned parallel to the wound surface, usually along lines of maximum tension. The presence of collagen and its arrangement contribute to tissue strength.

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38
Q

T/F: When the wound defect is filled and homeostasis of collagen production and collagen degradation is achieved, macrophage and fibroblast numbers are reduced by apoptosis, and tissue maturation and remodeling begin.

A

True

39
Q

__________ ________ residing above the basement membrane of the epidermis and lining hair follicles and the sweat and sebaceous glands facilitate reepithelialization.

A

Suprabasal keratinocytes

40
Q

There is rapid reepithelialization in _______ injuries, such as an abrasion, as the basement membrane and epidermal appendage populations of ___________ remain available across the entire wounded area to participate in the repair.

A

superficial; keratinocytes

41
Q

T/F: In full-thickness wounds reepithelialization can only occur through centripetal movement of the keratinocytes from the wound margins.

A

True; in full-thickness wounds there is no residual epithelium, or epidermal appendages, from which keratinocytes can be recruited. In wounds of similar surface area, it is this last type of injury that requires the longest duration to heal, because reepithelialization can only occur through centripetal movement of the keratinocytes from the wound margins.

42
Q

Keratinocytes stimulate __________ to synthesize and release growth factors and cytokines, which in turn stimulate _________ proliferation.

A

fibroblasts; keratinocyte

43
Q

Keratinocytes synthesize and release __________, __________, and __________ _________ to clear a path across the wound surface.

A

collagenases, proteases (MMPs), and plasminogen activator

44
Q

T/F: keratinocyte migration is best enhanced by a dry environment.

A

false; keratinocyte migration is best enhanced by a moist environment, because the drier the environment, the thicker the eschar. Migration is impaired by fibrin (eschar), by inflammatory products, and by the presence of exuberant granulation tissue

45
Q

In what ways does new epidermis differ from uninjured skin?

A

The new epidermis differs from that found in uninjured skin; it lacks rete pegs, which anchor it into the underlying connective tissue matrix; and in full-thickness wounds it lacks a dermal layer, without which there is a loss in tissue strength and elasticity. There is no regeneration of lost epidermal appendages such as sweat glands and hair follicles.

46
Q

Contraction usually begins in full-thickness wounds in the _______ following injury, and in areas with loose skin, rates of contraction can be as high as _____________.

A

second week; 0.75 mm per day

47
Q

T/F: At the conclusion of contraction, myofibroblasts either disappear by apoptosis or revert back to a fibroblastic phenotype.

A

True

48
Q

How does wound contraction occur?

A

Fibroblasts differentiate into myofibroblasts (facilitated by TGF-β1 released from macrophages and keratinocytes) which form specialized connections between themselves and molecules, including collagen and fibronectin, within the ECM at the wound’s edges. When the actin filaments within the myofibroblast contract, force is transmitted through these connections to the edges, causing wound contraction. Fibroblasts lay down collagen to reinforce the contracted wound.

49
Q

T/F: The remodeling and maturation phase begins during the second week of repair and ends in the formation of scar tissue 1 to 2 years later.

A

True

50
Q

T/F: The collagen deposited during the period of fibroplasia is oriented randomly, providing minimal tissue strength.

A

True; MMPs (collagenase, stromelysins, and gelatinases), which are derived from macrophages, epithelial cells, endothelial cells, and fibroblasts within the ECM, are responsible for the degradation of collagen within the wound. Collagen fibers, which were once haphazardly arranged, are reestablished in bundles, cross-linked, and aligned along lines of tension
by fibroblasts to progressively increase the tensile strength.

51
Q

There is a gradual gain in tissue strength from 20% of that of normal tissue at ___________, to 50% within ________, and ___ to ___ of the strength of original tissue at the conclusion of maturation.

A

3 weeks; 3 months; 70% to 80%

52
Q

T/F: Acute wounds in horses contract in size in the first 1 to 2 weeks.

A

False; acute wounds in horses, regardless of their location, expand in size in the first 1 to 2 weeks because of the tensional forces of the adjacent tissues. Contraction usually begins in full-thickness wounds in the second week following injury.

53
Q

Wounds on the body contract more efficiently (__ to ___ mm/day) than those located on the legs (___ mm/day).

A

0.8 to 1 mm/day; 0.2 mm/day

54
Q

T/F: Soil components have been shown to significantly reduce the number of bacteria needed to result in an infection.

A

True; soil components have been shown to reduce white blood cell effectiveness, decrease humoral defenses, and neutralize antibodies, thereby significantly reducing the number of bacteria needed to overburden the host’s immune system. It has been reported that contamination with as few as 100 microorganisms in the
presence of soil can result in infection.

55
Q

T/F: The production of excess granulation tissue can be traced back to the horse’s inefficient protracted remodeling phase.

A

False; The production of excess granulation tissue can be traced back to the horse’s inefficient protracted inflammatory phase, which leads to an excessive proliferative phase in which fibroblasts retain their synthetic role rather than differentiate into myofibroblasts or disappear

56
Q

How does TGF promote formation of exuberant granulation tissue?

A

TGF-β1 enhances migration and proliferation of fibroblasts and subsequent collagen production. it also delays fibroblast apoptosis and is an inhibitor of keratinocytes..

57
Q

T/F: equine amnion applied as a dressing has been shown to decrease development of granulation tissue and to accelerate epithelialization.

A

True

58
Q

T/F: Of the seven types, those with the greatest risk of developing infection are caused by sharp objects (e.g., an incision, a laceration caused by a nail).

A

False; Of the seven types, those with the least risk of developing infection are caused by sharp objects (e.g., an incision, a laceration caused by a nail). Contusion and crush injuries, which often include vessel thrombosis, are those most prone to infection. Puncture wounds, although seemingly innocuous, often develop infection because the puncture tract heals at the surface before the deeper soft tissues, thereby creating an ideal environment for bacterial growth.

59
Q

What is the purpose of early wound debridement?

A

To reduce bacterial numbers, foreign debris, and the necrotic tissue that would otherwise need to be removed during the cellular inflammatory phase

60
Q

T/F: Wet-to-dry dressings are a type of nonenzymatic, chemical debridement.

A

False; Wet-to-dry dressings mechanically débride the surface of the wound when removed without re-wetting. It may also be considered a form of autolytis debridement; autolytic débridement is achieved by placing an occlusive dressing over the wound, trapping the body’s own proteases within the wound to liquefy necrotic tissue.

61
Q

What are the various forms of non-surgical, mechanical debridement?

A

Wet-to-dry dressings

wound irrigation at 7 - 15 psi

62
Q

What are the tools available for surgical debridement?

A

scalpel, CO2 laser, or hydrosurgical unit

63
Q

T/F: Granulex spray, meat tenderizers containing papain and bromelain, and papain/urea-based proteinase are examples of autolytic débridement agents.

A

False; granulex spray, meat tenderizers containing papain and bromelain, and papain/urea-based proteinase are examples of chemical débridement agents.

64
Q

T/F: Granulex, which contains trypsin, peruvian balsam, and castor oil, is reported to hydrolyze proteins, increase perfusion, and promote epithelialization.

A

True

65
Q

T/F: Collagenase-containing products digest collagen, elastin, and fibrin.

A

False; Collagenase-containing products digest collagen and elastin but do not degrade fibrin. The papain/urea combination degrades fibrin and denatures collagen and skin.

66
Q

T/F: Maggots produce potent proteolytic enzymes and can consume up to 75 mg of necrotic tissue per day.

A

True (sterile maggots from the common green bottle fly Lucilia sericata)

67
Q

Triple antibiotic ointment
(bacitracin, polymixin B, and neomycin) and silver sulfadiazine (SSD) have ______ spectrums of activity, but silver sulfadiazine, unlike triple antibiotic, is effective against _____________ and ________.

A

broad; Pseudomonas spp. and fungi.

68
Q

T/F: Triple antibiotic ointment
(bacitracin, polymixin B, and neomycin) and silver sulfadiazine (SSD) have both been reported to increase epithelialization
but both may decrease wound contraction.

A

True

69
Q

Nitrofurazone ointment has ______ spectrum of antimicrobial activity, but it has also been shown to _________ epithelialization and to _____ wound contraction.

A

broad; decrease; delay

70
Q

How is PRP suggested to be beneficial in wound healing?

A

Platelets are rich in TGF-β, PDGF, epidermal growth factor (EGF), transforming growth factor-α (TGF-α), VEGF, serotonin, and histamine. They also secrete fibrin, fibronectin, and vitronectin, which act as provisional matrix and provide a surface for epithelial migration.

71
Q

T/F: Ketanserin-containing products (Vulketan gel) block serotonin-induced macrophage suppression and vasoconstriction and can be used during the inflammatory phase to promote a strong inflammatory response.

A

True

72
Q

What is the mechanism of action of aloe vera?

A

Acemannan, the active ingredient of aloe vera, stimulates macrophages to release fibrogenic and angiogenic cytokines. its use can be beneficial during the inflammatory phase and early period of fibroplasia and will accelerate the development of granulation tissue over exposed bone.

73
Q

T/F: Lanolin cream may be useful to increase the rate of epithelialization.

A

True

74
Q

What are the effects of glucocorticoids on wound healing?

A

Systemic and local use of glucocorticoids have global effects: decreased fibroblast proliferation, protein synthesis, and wound contraction; inhibition of
keratinocyte growth factor (KgF) production; and reduced angiogenesis.

75
Q

How might NSAIDs negatively impact wound healing?

A

Administration of nonsteroidal anti-inflammatory drugs (NSAIDs), through repression of cyclooxygenase (COX) activity, has been implicated to adversely affect migration and degranulation of neutrophils, angiogensis, infection rate, and healing.

76
Q

This cytokine is released from macrophage, lymphocyte, fibroblast, and endothelial cells. Its major function is
differentiation and maturation of hematopoietic stem cells.

A

Colony-stimulating factor (CSF)

77
Q

This cytokine is released from monocyte, macrophage, lymphocyte, and mesenchymal cells.
Its major function is
proinflammatory; release of other cytokines; inhibit fibrosis.

A

interferon (IFN)

78
Q

This cytokine is released from all nucleated cells, in particular macrophage and lymphocytes. Its major function is
proinflammatory; enhances epithelialization, angiogenesis, and remodeling.

A

Interleukin (IL)

79
Q

This cytokine is released from macrophage, lymphocyte, and mast cells.
Its major function is
proinflammatory; enhances angiogenesis, epithelialization, and remodeling.

A

Tumor necrosis factor (TNF)

80
Q

This cytokine is released from fibroblasts. Its major function is as a mediator of TGF-β activity (cell proliferation and ECM accumulation).

A

Connective tissue growth factor (CTGF)

81
Q

This cytokine is released from platelets, and also saliva. Its major function is epithelialization; chemotactic and mitogenic to fibroblast; protein and MMP synthesis (remodeling);.

A

epidermal growth factor (EGF)

82
Q

This cytokine is released from macrophage and epithelial cells. Its major function is angiogenesis.

A

Transforming growth factor-α

TGF-α

83
Q

This cytokine is released from inflammatory cell, fibroblast, and endothelial cells. Its major function is chemotactic and mitogenic to fibroblast and epithelial cell; protein synthesis; angiogenesis.

A

Fibroblast growth factor (FGF)

84
Q

This cytokine is released from the liver and platelets. Its major function is chemotactic and mitogenic to epithelial cell; migration of epithelial cell; fibroblast proliferation, protein and GAG synthesis

A

insulin-like growth factor (IGF)

85
Q

This cytokine is released from fibroblasts. Its major function is chemotactic and mitogenic to epithelial cell

A

Keratinocyte growth factor (KGF)

86
Q

This cytokine is released from platelets. Its major function is chemotactic to inflammatory cell and fibroblast; mitogenic to mesenchymal cell; protein synthesis, contraction?

A

Platelet-derived growth factor (PDGF)

87
Q

This cytokine is released from platelet, lymphocyte, mast cell, monocyte and macrophage, endothelial cell, epithelial cell, and fibroblasts. Its major function is chemotactic to inflammatory and mesenchymal cell; fibroblast proliferation; protein synthesis; ECM deposition (inhibition of MMP; induction of TIMP); wound contraction

A

Transforming growth factor-β

TGF-β

88
Q

This cytokine is released from macrophage, fibroblast, endothelial cell, and epithelial cells.
Its major function is angiogenesis.

A

Vascular endothelial growth factor (VEGF)

89
Q

_____________ dressings were designed to provide moisture to a wound that has dried out. They are completely occlusive and provide an excellent environment for autolytic débridement, white blood cell migration, and thermal regulation, and they thus result in improved wound healing.

A

Hydrogel; composed of water, glycerin, and polymers. They conform to the wound, are nondrying, and provide a bacterial barrier and, eventually, a moist environment.

90
Q

Calcium alginate dressings are used primarily for the ___________ phase of wound repair. They are made from alginate, a derivative of seaweed. The calcium in the dressing interacts with sodium in the wound, providing a wound exudate that stimulates myofibroblasts and epithelial cells and speeds wound homeostasis.

A

granulating

91
Q

Topical dressings such as collagens and maltodextrins are designed for use in the __________ stage of wound repair.

A

granulating

92
Q

_____________ dressings provide a moist environment and thermal regulation that will enhance epithelialization while minimizing exuberant granulation tissue. The dressings should not be used in the presence of infection.

A

Semiocclusive foam

93
Q

in vitro studies have shown that hydrocortisone ___________ plasminogen activator inhibitor-1 and
____________ plasminogen activators.

A

upregulates; downregulates

Surgical Biology (8 decks)

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