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- protein precursor to filaggrin
- found in the s. granulosum
acts as glue to stabilize s. granulosum
What are ogland bodies and where are they found?
- large amount of protein-bound lipids
- s. lucidum
where does keratinization begin?
- specialized appendages regulating:
- -pain stimuli
- Adnexa include:
- -hair follicle
- -apocrine sweat glands
- -eccrine sweat glands
- -sebaceous glands
- -nerves of epidermis
- Separated from epidermis by basement membrane
- Intricate connective tissue network 75% collagen
- -Nerve bundles
- -Sensory receptors
- -Vascular elements
- Maintains structural integrity of dermis
- Vital to wound healing & scar formation
- Synthesize connective tissue proteins for collagen & elastin
- Synthesize ground substance matrix for glycosaminoglycans
Relaxed skin tension lines
- Related to underlying musculature & osseous structures
- Associated with creases in the skin with normal flexion and extension
- Greatest ability to stretch and relieve tension in perpendicular direction to RSTL
- Not greatly defined in foot and ankle
- Lines of maximal and minimal movement
- Very important in incisional approach and wound healing
- If an incision is placed perpendicular to RSTL then maximum tension = stretched and hypertrophic scar
- Incisions parallel or within RSTL = less tension and scarring
- If cannot be within RSTL make incision in an oblique fashion
- If allowable incision should be within RSTL
- If not attempt for oblique to RSTL
- If crossing a joint try and curve incision
- Consider preoperatively:
- -Skin characteristics
- -Underlying anatomic structures
- -Location of incision
What normal object is NOT seen on radiograph?
vaccume assisted closure of a wound
- 130 mmHg continuous
- Sub atmospheric pressure
- Utilizes negative pressure to promote wound healing.
- Wound dressing “open cell” foam surface to promote granulation tissue.
- Can be used for variety of chronic and acute wounds
- Can be used to promote granulation tissue
- Stimulates angiogenesis.
- Oxygenation levels greater than 40mm Hg required for wound healing.
- Less than 30mm Hg results in impaired oxygenation and decreased wound healing.
- HBO increases oxygenation to soft tissues.
- Improves neutrophil function, facilitates fibroblast cell division, increases collagen formation, and increases capillary budding
How many organisms for a wound to be consider infected?
Positive wound cultures of surgical wounds as high as _____%?
What are the 2 most common species of bacteria to infect a wound?
staph and strep
Post op infection rate for clean, uncontaminated surgery is _____%:
what is the triad for wound infection?
- receptive host
- contamination of microorganisms
- wound culture medium
Wagner Classification of Wounds:
What factors help platelets initiate inflammatory stage?
PDGF and TGF-B
Macrophage Production of additional cytokines:
- Tumor necrosis factor alpha
What are the 4 stages of wound healing?
How long does each last?
- 1. Hemostasis: instantly- minutes
- 2. Inflammation(Substrate): Last 5-7 days
- 3. Proliferative: Day 5-21
- 4. Remodeling: 3 wks- 1 year
2. Inflammatory stage
- Begins at incision/injury
- Lasts 5-7 days
- Neutrophil migration
- Macrophage migration
- Cytokine secretion and recruitment of fibroblasts and endothelial cells
When do neutrophils get to a wound?
Proliferative Stage (3)
- 5-21 days
- Fibroblast migration and proliferation
- Collagen deposited
- Endothelial cells assemble microvascular structures
- Glycosaminoglycans make up the connective tissue matrix
- Loose matrix of collagen, fibronectin and hyaluronic acid
When do fibroblasts peak?
- ≈3 weeks – 1 year
- Lattice like collagen network
- Laying down of scar tissue
- Transformation of capillaries and fibroblasts to relatively acellular type I collagen bundles
What types of wounds is contraction most efficient on?
What does contraction begin on a wound?
following 3-4 days
-Begins within hours of injury
-Initiated by platelet release of epidermal growth factor
-Begins at wound edge and migrates centrally
-Continues until epidermal surface is completely restored
What is a major disadvantage to epithelialization?
- unstable quality of final wound and fragility
- *any for of minor trauma can cause recurrent ulceration
What is peak tensile strength in a wound?
60 days post injury
A healed wound will reach approx ___% of tensile strength
How does hyponatremia affect wound healing?
delay fibroblastic activity--> decreased wound strength
What does Vitamin C do in wound healing?
- Ascorbic acid
- Vit C and iron are required for hydroxylation of lysine and proline (collagen)
- Vitamin C and Lysine which crosslink and stabilize the triple helix structure of collagen
What does Vitamin A do in wound healing?
- retinoic acid
- modulates collagen production and degradation
What is Vitamin E role is wound healing?
- potent antioxidant
- alpha tocopherol
- accelerate dermal and bone healing
Zinc in wound healing
deficiency related to poor wound healing if deficient
What will happen is a diabetics insulin is >200mg/dl?
- decrease in phagocytosis
- decrease in killing of bacteria
What are some complications to diabetic wounds? (intrinsic factors)
-Decreased host resistance to bacteria
- -Metabolic differences – hyperglycemia and
- insulin deficiency/resistance
- -BS > 200mg/dl = ↓ phagocytosis and
- decreased killing of bacteria
-Insulin deficiency = ↓ collagen production and wound tensile strength
-Decreased fibroblast reproductive capability
How does insulin deficiency affect wounds?
decrease collagen production and wound tensile strength
What are some extrinsic factors of wound healing?
- -Competes with new tissue for nutrients and oxygen
- -Lactic acid production lowers pH and furthers tissue breakdown
- Smoking!-vasoconstrictive effect due to nicotine
How does hypovolemia affect wound healing?
Glucocorticosteroids affect on wounds healing(6):
Inhibit cellular proliferation
Inhibit tissue growth
Inhibit inflammatory reaction
Inhibit fibroblasts proliferation
Reduce collagen production
How do steroids affect wound healing?
- Steroids break down tissue fat and proteins and
- thus inhibit cellular proliferation, tissue growth and DNA synthesis.
What stage do steroids have greatest effect?
Antimicrobials(3) and wounds
Hydrogen Peroxide and negative effect on wound healing(4):
-Cytotoxic to bacteria and host tissue
-Retards wound epithelialization
-Can lead to necrosis and decreased microcirculation
-May allow invasive flora to overtake normal inhibitory flora of wound
Blocks formation of vitamin K and vitamin K dependent clotting factors
inactivate thrombin inhibiting blot clotting
decreases platelet aggregation
What is an exudate?
fluid that filters from circulatory stem to a wound
What are 4 things an exudate may contain?
- plasma proteins
What do exudates due? (4)
- Dilute toxins of dead cells
- limit use; prevents additional injury
- provide blood cells and nutrients to site of injury
- carry away toxins and waste
Serous wound exudates (4)
- mild inflammation
- usually clear
- little protein
- like water
Purulent Wound Exudates(7)
-Yellow to green
-Often has odor
Fribinous Wound Exudates (3)
- Fibrinogen and fibrin
- white to yellow in color
Hemorrhagic wound exudates (2)
Inflammation fever is caused by what?
release of cytokines in acute phase
inflammation leukocytosis is caused by what?
migration of neutrophils to phagocytose debris