module 1 integumentary healing lorello Flashcards
(76 cards)
1
Q
5 wound healing models
A
- Superficial wound healing
- Partial-thickness wound healing
- Full-thickness wound healing
- Primary intention
- Delayed primary intention
2
Q
primary intension and delayed primary intention
A
discussed in regards to surgical wounds
3
Q
based on depth of wound phases of healing
A
superficial
partial thickness
full thickness
4
Q
- Epidermis only
- Healing time: 3-7 days
- Outer injured epithelial cells peel away
- Seldom clinically significant
- sunburn that did not blister
A
Superficial Wound
5
Q
- Involves the entire epidermis
- Involves the papillary layer of the dermis
epidermis and part of dermis
A
Partial Thickness Wound
6
Q
- Involves the entire epidermis
- Involves the entire dermis
- Papillary
- Reticular
- Can involve subcutaneous tissue
A
Full Thickness Wound
7
Q
dermis does not _______ , it repairs
A
dermis does not regenerate, it repairs
scar formation occurs
8
Q
epidermis is constantly ________
A
regenerating
9
Q
partial or full involves more ______ than regenerate
A
repairs
10
Q
hypertrophic scar only occurs in _____
A
humans
11
Q
3 phases of healing
A
inflammatory
proliferative
remodeling
12
Q
Phases of Healing
what cells in each of the following phases?
inflammatory
proliferative
remodeling
A
- Inflammatory - platelets, fibrin, neutrophils, macrophages, mast cells
- Proliferative - fibroblasts, myofibroblasts, endothelial cells, keratinocytes
- Remodeling - fibroblasts
13
Q
small, irregularly shaped clear cell fragments which circulate in the blood and are involved in hemostasis
A
Platelets
14
Q
phagocytic cells that clean up debris and bacteria
A
neutrophils
15
Q
white blood cell that in response to inflammation will differentiate into macrophages
A
monocytes
16
Q
responsible for phagocytosis of debris, secrete GF that stimulate angiogenesis
A
macrophages
17
Q
cells that form the endothelium (lining of blood vessels)
A
Endothelial cells
18
Q
produce protein fibers (collagen, elastin) and extracellular matrix (ECM)
A
Fibroblasts
19
Q
cell that is differentiated from a fibroblast. Contains an actin and myosin contractile system similar to what is found in smooth muscle
A
Myofibroblasts
20
Q
predominant cell found in the epidermis
A
Keratinocytes
21
Q
specialized secretory cell that helps to promote fibroblast proliferation
A
Mast cells
22
Q
- Naturally occurring proteins (polypeptides)
- Mediate and regulate tissue deposition
- Can act on distant cells, adjacent cells, or themselves
- Can cause cell growth, cell migration, regulatory functions
A
Growth Factors
23
Q
Epidermal growth factor (EGF)
A
Stimulates angioblast, fibroblast, and keratinocyte proliferation
Chemotactic agent for fibroblasts and keratinocytes
24
Q
Keratinocyte growth factor (KGF)
A
Stimulates keratinocyte proliferation
25
Fibroblast growth factor (FGF)
Stimulates angiogenesis and epithelialization
Stimulates fibroblast growth and collagen production
26
Platelet-derived growth factor (PDGF)
Chemotactic factor for macrophages and PMNs
Stimulates angioblasts, fibroblasts, keratinocytes, and macrophages
Stimulates matrix production and angiogenesis
27
Granulocyte-macrophage colony-stimulating factor (GM-CSF)
§ Enhances wound contraction
§ Stimulates keratinocyte proliferation and migration
§ Stimulates angiogenesis
28
Transforming growth factor β (TGF-B)
§ Family of growth factors made by fibroblasts, macrophages, keratinocytes, and platelets
§ Regulates matrix formation and collagen synthesis
§ Stimulates angiogenesis and epithelialization
§ Involved in scar formation
29
Tumor necrosis factor α (TNF-α)
§ Stimulates fibroblasts
§ Activates neutrophils
§ Stimulates inflammatory mediators
§ Stimulates angiogenesis
§ Levels are increased in chronic wounds
30
Interleukin-1
§ Stimulates fibroblasts and epithelial cells
§ Stimulates collagen synthesis
§ Stimulates angiogenesis
§ Chemotactic factor for inflammatory mediators
31
Vascular endothelial growth factor (VEGF)
* Powerful stimulator of angiogenesis
* Stimulates granulation tissue formation and epithelialization
* Promotes collagen deposition
32
Insulin-like growth factor I
* Reverses steroid-impaired wound healing
33
* Begins at time of injury and can last 2-
5 days
* Clotting takes place in order to obtain
hemostasis
* Factors are released to rid wound of
debris, bacteria and damaged tissue
* Wound characterized by redness,
warmth, pain, edema, decreased ROM
Inflammatory Phase
34
* 1st step dedicated to hemostasis (clotting cascade)
* Clotting and vasoconstriction to reduce blood loss
* Breaking down pre-existing tissue scaffolding
* Clean-up of cellular, extracellular, pathogen debris
Inflammatory Phase
35
* Epidermal barrier is disrupted
* Keratinocytes release IL-1(1st signal to other cells of damage)
* Platelets are activated by collagen that is exposed when injury occurs
* Trigger vasoconstriction of the injured vessels
Inflammatory Phase
36
* Hemostasis
* Clot is formed comprised of cytokines, GF’s, fibrin molecules, fibronectin, vitronecin,
and thrombospondins (clotting cascade proteins)
* Serves as a scaffolding for the migration of leukocytes, keratinocytes, fibroblasts, and
endothelial cells
* Reservoir of growth factors
Inflammatory Phase
37
* Platelets secrete multiple cytokines and growth factors
* EGF, PDGF, TGF-β, IL-1
* Attracts neutrophils to the wound
* Monocytes are transformed into macrophages
Inflammatory Phase
38
* Wound Space Hypoxia
* Vasoconstriction causes decrease in O 2
* Hypoxia is a key signal that controls wound healing
* Neutrophils, macrophages
* Stimulates endothelial cells - angiogenesis
* Causes a shift to anaerobic glycolysis = ↑ lactate production
* Wound becomes hyperlactic → acidotic
Inflammatory Phase
39
Necrotic tissue WILL or WILL NOT allow the wound to move into the next phase of healing?
Necrotic tissue WILL NOT allow the wound to move
into the next phase of healing
You need oxygen
40
* Neutrophils - 1° cell that cleanses the wound
* Migrate into the wound within 24 hours of injury
* Phagocytic cells that clean debris and bacteria
* Hypoxic environment
Inflammatory Phase
41
* Macrophage - important throughout all phases of healing
* Activities during the inflammatory phase initiate angiogenesis and granulation tissue
formation during proliferation
* Phagocytosis of debris - excrete lactic acid
* Secrete collagenases - debridement in preparation for new collagen
Secrete GF’s
* VEGF
* TNF-β
* IL-1
promotes endothelial migration and proliferation
Inflammatory Phase
42
* Mast cells
* Promote fibroblast proliferation - TNF-α
* Releases histamine
* Vascular dilation – permeability and slight edema
* Produce heparin - stimulates endothelial cells
Inflammatory Phase
43
* Temperature
* Vasodilation of surrounding tissue – increased tissue perfusion aids in moving cells to
the injury
* ↑ temperature
* Injured nerve endings cause reflex hyperemia
* ↑ temperature
* Increases in cellular metabolism
* ↑ temperature
* If by the 4th day there isn’t a decrease in temperature - possible sign of infection
Inflammatory Phase
44
* Current of Injury
* All body cells posses their own currents
* Transport of ions through ion pumps
* Du-Bois Reymond detected electrical fields on a cut on his fingertip over 160 years ago
* This existence of endogenous wound electrical fields has been confirmed in all wounds
Inflammatory Phase
45
* Current of Injury
* Current flowing between normal and injured tissue is a stimulus for the repair process
* (-) polarity attracts fibroblasts
* Increases fibroblast proliferation and collagen synthesis
* Absence of current may lead to chronic wound healing
* Use of electrical stimulation may mimic the current of injury and accelerate/restart the
repair process
Inflammatory Phase
46
Proliferative Phase
>25 types of collagen have been
discovered
* Numbered in the order of their
discovery
* >25 types of collagen have been
discovered
* Numbered in the order of their
discovery
* Type I - dermis, bone, tendon, fascia,
sclera, IV disk
* Type II - hyaline and elastic cartilage
* Type III - smooth muscle, arteries,
lung, uterus, kidney
* Type I - dermis, bone, tendon, fascia,
sclera, IV disk
* Type II - hyaline and elastic cartilage
* Type III - smooth muscle, arteries,
lung, uterus, kidney
47
Proliferative Phase
Ground Substance
* Occupies the space between cells and fibers
* Viscous, clear substance with high water content
* Consists of glycosaminoglycans (GAG’s), proteoglycans, and multi-adhesive
glycoproteins
48
Proliferative Phase
Angiogenesis
* Restoration of vascular integrity
* Macrophages induce this process by releasing TNF-α, VEGF
* New capillary buds arise from intact blood vessels
* Endothelial cells proliferate and grow into the wound space
* Angioblasts are endothelial precursor cells
49
Proliferative Phase
Endothelial cell activation and survival
basement membrane degradation
endothelial cell proliferation and migration
tube formation elongation and remodeling
The angiogenic process
50
Proliferative Phase
* New capillary bed fills the wound
space
* Supplies oxygen and nutrients to
heal wound
* Capillary loops have the
appearance of granules
Making _______ tissue which is very fragile
granulation
51
Proliferative Phase
Granulation tissue
* Matrix metalloproteases (MMPs)
-Proteases produced by neutrophils,
macrophages, fibroblasts, and
keratinocytes
-Degrade the debris formed during
inflammation
* Very fragile
* Trauma may induce bleeding
Matrix metalloproteases (MMPs)
52
Proliferative Phase
* Myofibroblasts connect to the wound margin to pull the dermal layer inward
* Closes the wound
Contraction - DERMIS
53
Proliferative Phase
* Re-epithelialization - EPIDERMIS
* Re-establishment of an intact epidermis over the newly formed tissue
* Keratinocytes near the basal lamina migrate across the granulation tissue
* Epithelial migration from intact hair follicles and sebaceous glands
54
Remodeling Phase
* Occurs for 6 months - 3 years post
injury
* Collagen becomes parallel and creates
stronger bonds
* Most endothelial cells, macrophages,
and myofibroblasts undergo apoptosis
55
Remodeling Phase
* Collagen created during proliferation - Type ____
* Type III collagen is lysed by tissue collagenases and replaced with Type ___
* Type I is a stronger collagen fibril
* Finely tuned balance between collagen synthesis and collagen lysis
Type 3 created in proliferation phase
Type 1 replaces type 3 in remodeling phase
56
Remodeling Phase
* Stress has a significant effect on scar remodeling
* Shape, strength, and pliability
* Collagen, elastin, and ground substance are affected by the direction and magnitude of mechanical stress applied to the scar (________Law)
wolfe's
57
Remodeling Phase
* Connective tissue is laid down in response to lines of stress
* Tension causes an increase in collagen fibers
* You need stress to increase the population of connective tissue cells to remodel the tissue
* Too much ______ will cause newly formed scar to pull apart
stress
58
Remodeling Phase
* Scar Formation
* Vascularity and cellularity diminish
* Scar becomes less ___ and flattens out
red
59
Remodeling Phase
* Ratio of collagen breakdown to production determines type of scar
* Breakdown ≥ rate of production = flat pliable scar
* Breakdown ≤ rate of production = hypertrophic scar
60
Remodeling Phase
* Hypertrophic scar
* Red, elevated, itchy
* Confined to original area of injury
61
Remodeling Phase
Keloid Scar
* Type of hypertrophic scar
* Extends outside the area of injury
* Tumor like appearance
62
Remodeling Phase
* Scar
* Essential and a hinderance
* Begins as highly cellular and vascular ⇒
acellular and avascular
* Changes to collagen
* Basket weave ⇒ small parallel bundles
Remodeling Phase
* Scar
* Essential and a hinderance
* Begins as highly cellular and vascular ⇒
acellular and avascular
* Changes to collagen
* Basket weave ⇒ small parallel bundles
63
Remodeling Phase
intact skin vs scar tissue
Intact skin
* Collagen (basket weave)
* Elastin fibers
* Ground substance
Scar tissue
* Collagen (bundles)
* Ground substance
64
Remodeling Phase
* Mature scar _____ % as strong as original
tissue
* Rete pegs lost with scar at epidermal-
dermal junction
80%
65
Remodeling Phase
* Scar heals centripetally
* Contracts at forces measured in tens
to hundreds of pounds
Remodeling Phase
* Scar heals centripetally
* Contracts at forces measured in tens
to hundreds of pounds
66
Primary closure
* Wound is cleaned of foreign material and edges are approximated
* Wound should be closed in 1–14 days
* Also known as healing by primary intention
67
Secondary closure
* Wound repair follows 3 phases
of normal wound healing
* Signs of progression through
phases
* Acute wound: within 2 weeks
* Chronic wound: within 30 days
* Also known as healing by
secondary intention
68
Delayed primary closure
* Wound is cleaned and observed for signs of infection
* Then closed with sutures
* Wound should be closed within 1–2 weeks of suturing
* Also known as healing by tertiary intention
69
Factors that Affect Wound Healing
Chronic wound
-Wound that deviates from the expected sequence of repair
* Time
* Appearance
* Response to appropriate treatment
Senescent cells
§ Cells cease to divide
§ Higher levels of MMPs
§ Lower levels of TIMPs
§ Tissue inhibitors of matrix metalloproteases
§ Leads to degradation of ECM
Greater numbers of inflammatory cytokines and chronic wound cells
Arrested current of injury
§ Current flowing between normal and injured tissue is a stimulus for the repair process
§ (-) polarity attracts fibroblasts
§ Increases fibroblast proliferation and collagen synthesis
§ Absence of current may lead to chronic wound healing
§ Use of electrical stimulation may mimic the current of injury and accelerate/restart the repair
process
70
Chronic Wound Physiology
Inflammatory Phase
Inadequate perfusion
* Vascular insufficiency
Chronic Inflammation
* Presence of foreign body in wound bed
* Repetitive mechanical trauma
* Cytotoxic agents
71
Chronic Wound Physiology
* Proliferative Phase
Diminished keratinocyte migration
* Lack of moisture
* Large surface area
* Rolled edges (epiboly), thickened edges, hypergranulation tissue
72
Chronic Wound Physiology
* Proliferative Phase
* Repeated trauma
* Repeated infection
Long-term wound hypoxia
* Decreased fibroblast production
* Negative impact on collagen production
73
Chronic Wound Physiology
* Remodeling Phase
Imbalance between collagen synthesis
* Overproduction = hypertrophic scarring
* Underproduction = wound breakdown, dehiscence
74
Factors That Affect Wound Healing
* Intrinsic Factors (underlying pathology)
Related to the medical status of the patient
* Age
* Chronic disease
* Perfusion
* Immunosuppression
* Neuropathy
75
Factors that Affect Wound Healing
* Extrinsic Factors (environmental)
Those that come from the environment that affect the body
* Medications - anticoagulants, immunosuppressive, steroids
* Nutrition - requires increase protein intake
* Irradiation - injury to fibroblasts and endothelial cells
* Chemotherapy - stop angiogenesis
* Psychophysiologic stress
* Wound bioburden and infection
76
Factors that Affect Wound Healing
* Iatrogenic Factors
Related to the way a wound is managed
* Local ischemia - pressure from bony prominence, compression
* Inappropriate wound care
* Trauma - sharp debridement, improper handling during dressing change
* Time to heal
