2: Principles of Wound Healing - Bennett Flashcards Preview

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Flashcards in 2: Principles of Wound Healing - Bennett Deck (23)
1

phases of wound healing

(injury)
inflammatory
proliferative
maturation

2

mechanisms of wound repair

- connective tissue deposition
- epithelization
- contraction

3

types of wound closure

- primary intention
- secondary intention
- delayed primary closure
- partial thickness (scratch or superficial abrasion)

4

characterized by hemostasis and inflammation

inflammatory phase
- collagen exposed, during wound deformation activates the clotting cascade
- damaged cells release thromboxane A2 and prostaglandin 2 alpha (vasoconstrictors)
- initial response limits the hemorrhage
- capillary vasodilation occurs due to histamine release and the inflammatory cells migrate to the wound bed

5

first response cell

platelets
- release epidermal growth factors, platelet derived growth factors, histamine
- stabilie wound through clot formation

6

EGF and PDGF regulate ...

EGF - cell growth, proliferation and differentiation
PDGF - cell growth and division of blood vessels

7

vessel adherence
diapedesis
chemotaxis
phagocytosis

- pavementing, margination
- movement through vessel walls
- chemical directive to injury site
- opsinization

- PMN (second response) migrate to wound for complement mediated opsonization of bacteria

8

most essential cell for wound healing

macrophages
- macrophages release TNF which stimualtes fibroblasts and angiogenesis
- TGF stimulates keratinocytes

9

increased blood flow and congestion is evident by increased number of red cells

inflammatory phase
- the increase in PMNs is also evident as well as increased prtn exudates

10

3 parts of proliferative phase

- epithelization
- angiogenesis
- collagen deposition

11

basement membrane damaged v. not damaged

intact = cells migrate in normal pattern, normal layers of epidermis restored in 2-3 d

destroyed = re-epitheliaztion from cells in periphery

12

what stimulates angiogensesis?

TNFalpha
- endothelial cell migrationa nd capillary formation
- maintains granular bed
- mmigration of capillaries delivers nutrients to wound bed

13

cytokines involved in granulation tissue formation during proliferative phase

- fibroblasts differentiate and lay down collagen fibers in varying patterns
- IGF, PDGF

14

histological features of proliferative phase

numerous fibroblasts
new capillary formation

15

describe maturation phase

- increased collagen and vascularity
- wound contraction
- wound reaches max strength at one year
- has tensile strength 30% of normal skin

16

major cells each phase

inflammation- neutrophils
proliferation - macrophages
maturation - fibroblasts and endothelial cells

17

4 wound healing principles

- vascular perfusion
- bacterial balance
- nutritional balance
- control contributing factors

18

parting of layers of surgical wound

wound dehiscence
due to: infection, hematoma, seroma, poor surgical technique, inappropriate closure technique, excessive motion at surgical site, pt non-compliance

19

side to side closure of wound

primary intention
ex: use sutures to reapproximate skin edges

20

wound is left open to granulate to closure

secondary intention

21

wound is left open for a period of time and then primarily closed

delayed primary closure

22

abnormal scar that extends beyond boundary of original skin injury

keloid
- raised, thickened growth associated with pruritus and pain
- scanning electron microsocopy reveals randomly organized collagen fibers in dense connective tissue matrix
- sternum, deltoid, upper back have increased susceptibility (elevated m and skin tension), also earlobes and post portion of neck
- 50% recurrence
- tx with compressive dressings, intralesional corticosteroid injections, cryosurgery, laser ablation

23

widened or unsightly scar that does not extend beyond original boundaries of wound

hypertrophic scars
- usually reach a certain size and then stabilizes or begins to regress

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