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Junior Basic Science 1/25/2011

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Presentation on theme: "Junior Basic Science 1/25/2011"— Presentation transcript:

1 Junior Basic Science 1/25/2011
Wound Healing Junior Basic Science 1/25/2011

2 3 Phases of Wound Healing
1. Inflammation- day 1-10 2. Proliferation-5 days-3 weeks 3. Remodeling-3 weeks-1 year

3 Inflammation Phase: Injury
Bleeding and vasoconstriction(5-10min), followed by vasodilation Plt plug formation and clotting Fibrin binds the plt plug and forms the provisional matrix (platelets+fibrin+fibronectin) Platelet degranulation (alpha and dense granules) -> PDGF and TGF-B Chemotaxis for inflammation

4 Inflammation PMNs-almost immediately, clear debris
Macrophages-Day 2-3 (essential) Fibroblast proliferation, endothelial cell proliferation (angiogenesis), and extracellular matrix production, and they recruit and activate additional macrophages. Lymphocytes

5 Proliferation Phase (5-21 days)
Fibroblasts-enter provisional matrix and initiate collagen synthesis Prominent cell type during this phase Macrophages->angiogenesis and neovascularization Collagen and proteoglycans or ground substance replaces the provisional fibronectin–fibrin matrix

6 Remodeling Phase (3wks-1 year)
Max collagen accumulation at 2-3 weeks. Only remodeling/crosslinking after 3 weeks. Type III collagen predominates early (days 1-3), but is replaced by type I 6 weeks-80% of final strength and 60% of original strength 8 weeks-max tensile strength (70-80%)

7 Collagen Need alpha-ketoglutarate, vit C, O2, and iron for hydroxylation of proline, and crosslinking of proline residues Proline is every 3rd amino acid. Lysine is abundant from hydroxylysine crosslinking Type I, most common and most abundant in healed wound D-penicillamine inhibits collagen crosslinking

8 Surgical Wound Healing
Primary Intention-Tensile strength is important in healing closed incisions Depends on collagen deposition and cross-linking Secondary Intention-Epithelial integrity is important in healing open wounds Dependent on granulation tissue (capillaries, fibroblasts and collagen) Migration from wound edges, sweat glands and hair follicles

9 Essential for wound healing
Moist environment- optimizes epithelial migration Oxygen delivery- Essential Avoid edema- edema causes decreased O2 in wounds Remove necrotic tissue- leads to infection

10 Factors affecting wound healing
Nutrition-Albumin <3 Infection Foreign body Drugs Diabetes Ischemia Aging Radiation Neuropathy


12 Scars Contain proteoglycans, hyaluronic acid, and water.
Keloids- AD, dark skinned. Collagen goes beyond original scar Hypertrophic scar- Collagen stays within scar Treatment: Steroids, silicone, pressure garments, XRT. Infants heal with little/no scarring-multifactorial, decreased inflammatory response, increase hyaluronic acid?

13 Chronic Wounds Pressure Sores- pressure over bony area, occurs when tissue pressure exceeds the capillary filling pressure of 25 mm Hg Tx: Pressure off loading, debridement, myocutaneous flap Leg ulcers- 90% due to venous insuff. Tx: Unna boot, elastic wrap Diabetic foot ulcers- 2nd MTP joint (Charcot’s joint). Neuropathy leads to increased pressure-> Ischemia Tx: Depends on extent of ulcer

14 Question The most prominent cell type in the 1st 24 hours of a wound is : PMN’s Macrophages Lymphocytes Fibroblasts

15 Answer PMN’s Most abundant in 1st 24 hrs, help clear debri

16 Question The most prominent cell type day 2-4? PMN’s Macrophages
Lymphocytes Platelets

17 Answer Macrophages Fibroblast proliferation, endothelial cell proliferation (angiogenesis), and extracellular matrix production, and they recruit and activate additional macrophages.

18 Question What is the most prominent cell type at 1 week? PMN’s
Macrophages Lymphocytes Fibroblasts

19 Answer Fibroblasts -Enter provisional matrix and initiate collagen synthesis. Days 5-21.

20 Question The most predominant type of collagen in the body? I II III

21 Answer Type I most common, seen in skin, bone, tendons, and healed wounds I II Cartilage III IV Basement membrane

22 Question Most abundant collagen in healing wound during 1st 24hrs? I

23 Answer Type III- Most abundant the first 48hrs, and is then replaced by type I.

24 Question What is the most important cell involved in wound healing?
PMN’s Macrophages Lymphocytes Fibroblasts

25 Answer Macrophages Essential, synthesizes cytokines and growth factors necessary for wound healing.

26 Question Maximal tensile strength of a wound occurs at: 3 weeks
3 months

27 Answer 8 weeks- Has 80-90% of original strength

28 Question What vitamin can you give to prevent the negative affects on wound healing? A D O K

29 Answer Vitamin A 25,000 UI daily

30 Question Peripheral nerves regenerate at: 0.01mm/year 0.1mm/day

31 Answer 1mm per day

32 Question The most important factor in the healing wounds by secondary intention is: Tensile strength Epithelial integrity Platelet activating factor cocaine

33 Answer Epithelial integrity- epithelial cells migrate from hair follicles, wound edges and sweat glands.

34 Question The most important factor in the healing wound by primary intention is: Double cheeseburger from McDonalds Tensile strength Epithelial integrity Platelet activating factor

35 Answer Tensile strength, not double cheeseburger
This is created by collagen cross linking

36 Question The dressing change regimen that will produce maximal debridement is: Wet-to-dry dressing changes with saline. Dressing changes with Xeroflo. Dressing changes with silver sulfadiazine. Dressing changes with an occlusive dressing.

37 Answer Maximal debridement is accomplished when the dressing is changed utilizing wet-to-dry dressings. Enzymatic agents, such as collagenase, may augment the debriding effect of wet to dry dressing changes.

38 Question Hypoxia in a wound stimulates: collagen synthesis contraction
ovulation angiogenesis epithelialization

39 Answer Angiogenesis

40 Question Cofactors necessary for successful hydroxylation of proline include all the following except: Vitamin C. Magnesium. Ferrous ion. α-Ketoglutarate. Oxygen.

41 Answer Magnesium

42 Question Local factors which invite wound infection include all of the following except: Foreign material. Radiation injury. Poor circulation. Disruption of fascia. Hematoma.

43 Answer Disruption of fascia
Depth of injury into the fascia has not been identified as a wound characteristic that predisposes to infection

44 Question Significant collagen synthesis first begins in a wound at:
2 to 4 weeks. 7 to 10 days. 0 to 12 hours. 12 to 24 hours. 3 to 5 days.

45 Answer Significant collagen synthesis begins in a wound at 3 to 5 days.

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