T1 Lecture 2: Fundamentals of Wound Management Flashcards
Wound healing brings about tissue repair and regeneration and its a fine tune process that culminates in formation of the ____
scar
What are the 4 stages of wound healing in order?
I Demand Rossies Memorize
- Inflammatory phase
- Debridement phase
- Repair
- Maturation/remodeling phase
With wound healing can more than one stage happen at the same time? Do all wounds go through all the phases or can they skip some?
• Significant degree of overlap
so more than one stage may be
occurring simultaneously
• ALL normally healing wounds
must undergo all stages of wound
healing regardless of
size/cause
True or False:
Normal wound healing can bypass certain phases of the 4 step wound healing process.
False
• ALL normally healing wounds must undergo all stages of wound healing regardless of size/cause
Describe what takes place in the first 3-5 days of wound healing, what phases are predominating causing this?
The lag phase of wound healing because inflammation and debridement predominate and wounds have not gained appreciable strength**
Inflammatory phase takes place first within __-__ days
0-5
______ is a protective response initiated by tissue damage
Inflammation
The Inflammatory phase of healing is characterized by the following: (4)
- Increased…..?
- Recruitment of …..?
- Release of _____ and ____
- Activation of these?
– Increased permeability of local blood vessels
– Recruitment of circulatory cells
– Release of growth factors and cytokines
– Activation of neutrophils, lymphocytes, fibroblasts & macrophages
1st response to any injury is?
Hemorrhage (TO BLEED DUHHH)
Describe the general process of inflammation
- Bleeding/Hemorrhage
- ______
- ____ ____
- Vasodilation
- ______ response
- Formation of ______
- Hemorrhage
- Vasoconstriction
- Fibrin clot
- Vasodilation
- Leukocyte response
- Formation of Platelets
During the inflammatory phase after injury takes place and the body responds with hemorrhage?
Describe what takes place next?
What quickly follows after that, why this is taking place?
Vasoconstriction (5-10 min.)
– Next step is to control hemorrhage = Fibrin clot
– Clot also occludes ruptured lymphatics and Prevent drainage/cause edema/localized inflammation = “Glues” wound edges together
After the vasoconstriction, what is next?
Vasodilation to Increased ______ _____
the vessels release ______ ____
(_____ acid cascade) & cellular components
This inflammation lasts ~ __ days
vascular permeability
inflammatory mediators
(arachidonic acid cascade)
~ 5 days
What takes place next in the sequence of inflammation after vasodilation?
State the first responders and then who comes next?
Leukocyte response – PMN’s = 1st responders then macrophages and then T-lymphocytes
Of the leukocytes who arrives first?
PMN’s (polymononuclear neutrophils) = 1st responders
After the leukocytes response next comes platelets and coagulation but these platelets are also responsible for producing?
several cytokines/growth factors important
for progression of wound healing
(Examples) PDGF, transforming growth factor – ⍺ & β, TNF-⍺ = chemotactic for these guys
To transition from inflammatory phase to debridement what takes place next?
White blood cells (The arrival of neutrophils ~6 hr. after wounding & monocytes ~ 12 hrs) leaking from blood vessels into wounds
What is the timing in terms of days with the debridement phase?
2-5 days
Generally, where does debridement take place and what does it cause?
W/in wound bed = Development of an exudate rich in WBC’s, wound fluid & necrotic tissue
Neutrophils Increase in number for 2 - 3 days and there job is to?
Job’s are to prevent infection & phagocytize organisms and debris
What is the significance of degenerating neutrophils in terms of what do they release and facilitate and stimulate?
Degenerating neutrophils release enzymes/toxic oxygen products = Facilitate breakdown of bacteria, extracellular debris/necrotic material & they stimulate monocytes
Compare and contrast monocytes and neutrophils and state who is essential for wound healing and who is not?
*Monocytes: Essential for wound healing (neutrophils/lymphocytes = NOT)!
What are monocytes main role?
Major secretory cells synthesizing growth factors that participate in tissue formation &
remodeling
Monocytes turn into ______ in wounds with __-__ hours
macrophages; 24-48
What are the 3 main roles of macrophages?
- Secrete ____ to removing ______ tissue, bacteria, and ____ ____
- Secrete collagenases removing necrotic tissue, bacteria and foreign material
- Secrete chemotactic & growth factors
- Macrophages also recruit mesenchymal cells, stimulate angiogenesis and modulate matrix production in wounds
What are chemotactic factors?
Chemotactic factors (i.e., complement, collagen fragments, bacterial endotoxins, and inflammatory cell products) direct macrophages to injured tissue
What do growth factors initiate?
Growth factors (i.e., platelet-derived growth factor, transforming growth factor-α, transforming growth factor-β, fibroblast growth factor, and interleukin-1) can initiate, maintain & coordinate formation of granulation tissue
_____ appear later in the debridement phase than neutrophils/macrophages
Lymphocytes
What do lymphocytes secrete in the debridement phase and what do they do?
- Secrete soluble factors that may stimulate or inhibit migration & protein synthesis by other cells
- Improve rate & quality of tissue repair
Name the growth factor and state their source? Which one is from macrophages?
BFGF
BFGF (Basic fibroblast GF)- From Macrophages/MC’s/T-lymphs
Name the growth factor and state their source? Which one is from macrophages?
EGF
EGF (epidermal GF)- From Plts/Macrophages
Name the growth factor and state their source? Which one is from macrophages?
KGF
KGF (keratinocyte GF)- From Fibroblasts
AKA growth Factor 7
Name the growth factor and state their source? Which one is from macrophages?
PDGF
PDGF (platelet derived GF)- From Plts./Macro./endothelial cells
Name the growth factor and state their source? Which one is from macrophages?
TGF alpha
TGF beta
TGF alpha (transforming GF)- From Macrophages/Plts/lymphs/hepatocytes
TGF beta (transforming GF)- From Macrophages/Plts/lymphs/hepatocytes
Name the growth factor and state their source? Which one is from macrophages?
VEGF
VEGF (Vascular Endothelial cell GF)- **From endothelial cells*
What 2 growth factors are not from macrophages?
- KGF-from fibroblasts
2. VEGF-from endothelial cells
During the Repair phase what days of wound healing does this take place during?
3-5 days to 2-4 weeks
What happens first with macrophages during the repair phase?
Macrophages stimulate fibroblast & DNA proliferation
(repair phase?)
Fibroblasts originate from?
Fibroblasts originate from undifferentiated mesenchymal cells in surrounding
connective tissue which leads to them Migrating into wound along strands of fibrin in wound clot
Fibroblasts Synthesize & deposit _____, _____, and ______ that mature into fibrous tissue. What environment do they prefer?
collagen, elastin & proteoglycans
• Prefers slightly acidic and oxygen rich (~20mm Hg) environment
______ infiltrate wound behind fibroblasts = and facilitate _______
– Relies on?
Capillaries; Angiogenesis
– Relies on interaction of extracellular matrix w/ cytokines that stimulate migration/proliferation of
endothelial cells
Capillaries infiltrate wound behind fibroblasts = Angiogenesis which increase _____ _____ in the wound to improve ______
Increase oxygen tension in wound = Improved fibroplasia
Combination of fibroblasts, new capillaries & fibrous tissue development results in
the formation of? __-__ days after wounding
bright red, fleshy granulation tissue ~ 3-5 days after wounding
______ _____ fills defects and protects wounds?
Granulation tissue
Granulation tissue serves 3 main functions?
– Excellent barrier to infection
– Serves as source of special fibroblasts
• Myofibroblasts = Use in wound contraction
– Surface for epithelial migration
What is the rate of at which granulation tissue is formed?
Formed at each wound edge at rate of:
0.4 to 1mm/day
During the repair phase, what step is next after healthy granulation tissue is formed?
Epithelialization = Mobilization, proliferation & differentiation of epithelial cells
Epithelialization of sutured wounds begins within __-__ hours and with an open wound it begins within __-__ days
sutured 24-48 hours
open wound 4-5 days
Open wound epithelialization begins within 4-5 days and requires?
requires granulation tissue to create a scaffold to crawl across
Migration of epithelial cells is random but guided by ____ ____. Migrating cells enlarge, flatten & mobilize, losing their attachments to the basement membrane &
other epithelial cells
collagen fibers
– Cells in the layers behind these altered cells migrate over them until they contact the wound surface
– Cells continue to slide forward until the wound surface is covered
– The migrating cells move under scabs & produce ______ = Dissolves the base of the scab so it can be shed
collagenase
Contact on all sides w/ other epithelial cells does what?
inhibits further cell migration = Contact inhibition
*Epithelialization occurs faster in a ____ environment than in a ____ one & will not occur over
______ tissue
moist; dry; nonviable
Epithelialization/migration is _____ dependent and related to ____ ____ –>
Energy-dependent & related to oxygen tension (Anoxia prevents epithelial migration & mitosis)
Wet-to-dry bandages debride newly formed epithelium, ______ re-epithelialization
delaying
During the repair phase after epithelization, what comes next?
Wound contraction = Size of wound is reduced d/t fibroblasts, reorganizing collagen in
granulation tissue & myofibroblast contraction at the wound edge
Wound contraction occurs simultaneously with _____ and ____ but is independent of ______
Occurs simultaneously w/ granulation & epithelialization but is independent of
epithelialization
(Repair Phase: Contraction)
Involves a complex interaction of cells, extracellular matrix & cytokines
– Significant _____ invasion into the wound is necessary for initiation of _____
fibroblastic; contraction
During repair/contraction
Centripetal, full-thickness skin edges are pulled inward by contraction
– wounds noticeably smaller by __-__ days post injury and progresses at a rate of ___-___ mm/day
5-9 days/ .6-.8mm day
When is the contraction phase of repair terminated?
When wound edges meet
What are some things that inhibit contraction?
If skin around wound = Fixed, inelastic, under tension
or when myofibroblasts are inadequate (i.e. insufficient granulation tissue)
During the maturation and remodeling phase:
How are strengths of the wound optimized?
d/t changes in the scar during the maturation phase
Wound maturation begins once? State the timing as well
adequate levels of collagen are reached
– 17 to 20 days after injury and may continue for years
During the maturation and remodeling phase:
Collagen fibers remodel w/ alteration of their orientation
& increased cross-linking to improve wound strength, what type of collagen increases and decreases during this?
Type I collagen increased & type III gradually decreases
When is the most rapid change in wound strength and what is it due to?
Most rapid gain in wound strength = Bet. 7 & 14 days after injury d/t rapid collagen
accumulation
– Wounds gain only about 20% of their final strength in the first 3 weeks after injury
True or False:
After a traumatic wound, normal tissue strength is fully gained back.
FALSE
• Slower increase in wound strength then occurs BUT normal tissue strength is never regained
– Only ~ 80% of original strength may be regained
