A 7 Wound healing Flashcards
how long does it take for vasoconstriction to occur after a wound has occurred?
10-15 minutes post wounding.
what activates both the intrinsic and extrinsic clotting cascade?
collagen exposure
What do thromboxane A2 and Prostaglandin 2A do?
they are 2 important vasoconstrictors in wound healing that are released from damaged cell membranes.
do platelets help with vasoconstriction or vasodilatation?
vasoconstriction.
Platelets release?
epidermal growth factor (EGF)
fibronectin
histamine
PDGF
what is fibrin?
the primary component in the matrix of the early wound which creates a stable plug/clot.(thrombin–>fibrinogen–>fibrin)
besides leading to the fibrin clot, what else does thrombin do?
increases vascular permeability, and facilitates the migration of inflammatory cells.
what does histamine, prostaglandins (E1 &E2), kinins, C3a, C5a, and leukotrienes have in common?
they all increase vessel permeability so that cells can move out during inflammation and infection.
which white blood cells are the first to migrate to the wound area?
PMN’s or neutrophils.
What helps signal the white blood cell to leave the blood vessel and move into the tissue?
TGF-beta
what are the 3 stages of wound healing?
1) hemostasis and inflammation
2) granulation and proliferation
3) remodeling and maturation
lymphokines and interleukens are considered classes of?
cytokines
How do growth factors work?
1) GF cellular receptor
2) phosphorylation of a kinase
3) second messenger
4) nuclear transcription
5) cell proliferation
How long does the hemostasis/inflammatory phase generally last?
2-5 days post accident
What is the first response cell to the damaged tissue?
platelets
What is considered to be the first leukocyte (second cell type) to arrive on scene?
the neutrophil because the platelet releases C5a which is a chemoattractant for neutrophils.
What is the result when ADP leaks out from the damages tissues?
platelet aggragation
prothrombin–> thrombin, fibrinogen–> fibrin.
what do thrombin and fibrin do?
1) thrombin increases vascular permeability/extravascular migration
2) fibrin is the primary component of the matrix in the early wound as it strengthens the platelet aggregate.
which factors contribute to vessel permeability?
thrombin histamine prostaglandins C3a C5a
what do neutrophils do?
phagocytosis
oxidative burst mechanisms
what are the third type of cells that migrate to the wound site?
macrophage
platelet–>neutrophil–>macrophage
what do macrophages release?
collagenases [debride the wound]
TNF [stimulate fibroblast and angiogenesis]
TGF [stimulates keratinocytes]
What time frame does the proliferative/granulation phase occur?
2 days to 3 weeks
_________are the most important mesenchymal cells in wound healing?
fibroblasts.
In order to fill in a gap produced by a wound, the cells migrate into the wound and lay down a sticky bed of proteins that consists of what?
laminin 5
T/F Fibroblast migrate across fibrils in the early wound.
False, they migrate ALONG and not ACCROSS.
for some reason she put an emphasis on this
What is the function of TIMP?
TIMP = tissue inhibitors of Metalloproteinases.
Recall that metalloproteinases break down the old matrix such as a scab to make new area)
which type of collagen predominates in early wound healing?
which type of collagen predominates in late wound healing?
early = type 3 collagen late = type 1 collagen
high lactate levels, low Ph, and hypoxia all stimulate what?
angiogenesis
what is considered the most potent angiogenic agent?
VEGF
List the order of cells that move to the wound area?
1) platelets
2) neutrophils
3) macrophages
4) fibroblasts
In what time frame does remodeling/maturation phase occur?
3 weeks to 2 years
collagen deposition reaches its peak in the wound by what time?
however, it is only ________% as strong?
1) 3 weeks
2) 15 percent
what is considered the most potent stimulant for collagen synthesis?
TGF beta
after complete renewal of the wound, the scar is only _____% as strong as the original?
80%
what percentage of normal skin is made up of collagen type 1?
80-90 %
T/F elastin is a major part of the wound healing process as it helps keep tension to prevent splitting?
False, recall that elastin is not a part of the new scar even though it is a part of normal skin.
Name 3 enzymes used for collagen breakdown?
1) Matrixmetalloproteins
2) collagenase
3) gelatinase
when does the scar reach maximum tensile strength?
at about 12 weeks. However, this is still only about 80% of normal.
What is first intention surgical repair of the skin?
wound healing by direct approximation such as with suturing.
what is second intention surgical repair of the skin?
wound left open to heal spontaneously
what is third intention surgical repair of the skin?
delayed wound closure.
Name vitamins/minerals (stuff) that affect wound healing?
vitamin K,A,C, zinc, protein deficiency, copper, cobalt, iron–>just trace elements…..
how does vitamin A affect wound healing?
decreased collagen and increased infection rate
how does vitamin C affect wound healing?
capillary fragility, unstable collagen
how does vitamin K affect wound healing?
clotting cascade
how does zinc affect wound healing?
decreased immune system
what is a Keloid scar?
excessive accumulation of collagen on the wound and beyond.
what is Hypertrophic scarring?
excessive accumulation of collagen on the wound only…
what is hypotrophic scarring?
insufficient accumulation of collagen of the wound
PDGF does what?
Chemotaxis
angiogenesis
wound contraction
TGF alpha & EGF (epidermal growth factor) do what?
keratinocyte migration
mitogenic fibroblasts
TGF beta does what?
angiogenesis
Promote collagen synthesis
FGF’s do what?
fibroblast and keratinocyte migration
angiogenesis
TNF does what?
activates Macrophages
angiogenesis
T/F IL’s 1 &2 are pyrogens?
True
Interferons (all)
activate macrophages
inhibit fibroblasts
