Flashcards in Wound Healing Deck (60)
Describe the difference between autocrine and paracrine signaling.
Autocrine is the production of signaling molecules by a specific cell and the molecules act only on that cell type. Paracrine molecules act on a range of cells.
Name 4 functions of neutrophils in the wound.
Killing of bacteria with reactive oxygen species, phagocytosis of bacteria, release of additional cytokines, breakdown of extracellular matrix via proteolytic enzymes.
Neutrophil killing of bacteria within the wound is dependent upon what?
High partial pressure of oxygen (40mmHg)
After approximately 48 to 96 hours after wounding, what is the primary leukocyte in the wound?
Name 4 cytokines and 4 growth factors released by Macrophages
AND 4 enzymes!
IL-1,6,8,TNF-alpha and FGF, EGF, TGF-beta, PDGF; MMP1, 2, 3, and 9
What’s the predominant cell type in the proliferative phase?
The proliferation phase from day____ to day _____.
Wound contraction is a function of transforming ___________ into ________________ in response to signaling from ________________.
Fibroblasts , myofibroblasts, TGF-beta
Grossly, the proliferative phase of healing is characterized by the development of ____________.
During the maturation phase of healing, the early granulation tissue is composed of primarily type ____collagen and as the phase continues and tension is applied to the wound the type of collagen switches to the more robust type ____.
The mucosa of the GI is composed of three layers. Name them
Epithelium, lamina propria, and muscularis mucosa
The esophagus does not have a serosal layer. Instead it’s outer layer is called the __________.
The submucosa is composed of what three types of collagen? Which type predominates and provides the majority of the tensile strength?
I, III, V and type I (68%)
Intra-abdominal sepsis can be responsible for the increased production of _____________which will result in the increased breakdown of mature collagen and the decreased production of new collagen.
How does fascial healing times compare to skin healing times?
Bladder regains 100% of its unwounded strength in _____days
4 Steps of wound healing
3 Stages: Inflammation, Proliferation, and Maturation. 4 steps: 1-Formation of a fibrin-platelet clot. 2-Recruitment of WBCs. 3-Neovascularization and cellular proliferation. 4-Tissue remodeling
3 phases of wound healing
inflammation, proliferation, maturation
3 classifications of burns and what separates them?
Partial (subdivided into -superficial partial (only epidermal) and -deep partial (epidermal and partial dermal)
& full thickeness
With respect to contamination and time, What is the threshold for developing an infection?
10 to 5th (10^5) colony-forming units per gram of tissue has long been considered the threshold for developing an infection with the time frame of this occurring in 6 hours or more
How many classes of wounds are there? And what are they?
Class I: 0-6 hrs old, minimal contamination and tissue trauma
Class II: 6-12 hrs old, microbial burden may not have reached a critical level
Class III: > 12 hrs old, microbial replication may have reached the critical level consistent with the development of an infection
Types of wound closure?
Primary (1st intention)
2nd intention (healing by contraction and epithelialization)
Secondary closure ("3rd intention")
Characteristics of Primary wound closure
Wound edges are apposed and allowed to heal with minimal gap with sutures, tissue glue, staples, a bandage or application of a graft soon after injury.
Class I wounds are considered amenable to primary closure. Class II wounds can be closed primarily if wound contamination/tissue trauma is minimal.
Characteristics of delayed primary closure
Appositional closure 3-5 days after wounding but before granulation tissue has been produced in the wound bed.
Indicated for mildy contaminated, minimally traumatized wounds that require some cleansing, debridement, and open management prior to closure.
Class II wounds
Characteristics of 2nd intention healing
Wound is left to heal through contraction and epithelialization. Drawbacks - New epithelium is fragile and easily abraded, wound contraction can be excessive, or wounds may fail to completely reepithelialize, leaving exposed or proliferative granulation tissue in the center of the wound. Indicated for dirty, contaminated, traumatized wounds in which cleansing and debridement is necessary but primary or delayed closure is prohibited.
Burn wound: 3 concentric zones?
Zone of destruction or coagulation; Zone of stasis; zone of hyperemia
A __________ area separates completely devitalized tissue from undamaged tissue
Zone of destruction or coagulation?
Excessive heat results in denaturation of cellular proteins and coagulation of blood vessels; Zone closest to heat source; Irreversible damage
Zone of stasis?
reduced blood flow and intravascular sludging; potentially reversible; further damage from hypoperfusion, edema, hypoxia, or infection can convert marginal tissues to nonviable tissue; Some vessels completely thrombosed→Thromboxane A2 produced → further vasoconstriction