Term
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Definition
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Term
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Definition
the more damage there is the more must be replaced with collagen and not the native tissue. collagen is reformed into a scar
basement membrane of the underlying ECM is not in tact |
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Term
| what are some of the down sides of scar tissue (2) |
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Definition
it is unable to perform the functions of the native tissue
it will never be more than 80% of the native tissue strength |
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Term
| when does scar tissue begin to form |
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Definition
| 24 hours after the injury |
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Term
| explain the process of scar formation (5) |
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Definition
endothelium and inflammatory cells (macrophages) release mediators to attract fibrobolasts
fibroblasts are stimulate to proliferate and deposit ECM and collagen
fibroblasts, deposited CT, and leukocytes make pink granular tissue
maturation and remodeling of fibrous tissue into collagen forms scar
scar is remodeled over time by matrix metalloproteins |
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Term
| what mediators do macrophages use to call in fibroblasts (3) |
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Definition
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Term
| what mediators stimulate for fibroblasts to proliferate |
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Definition
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Term
| matrix metalloproteinases: what is their function, what makes them |
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Definition
made by fibroblasts,epithelium, synovial joints.
break down protein (type III collagen) and replace it with type I collagen to reorganize the wound |
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Term
| how do matrix metalloproteinases work, how do they stop working |
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Definition
dependent on zinc
stored inactivated and are activated by plasmin (splits clots to limit size)
inactivated by tissue inhibitors of metalloproteinases (TIMPs) |
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Term
| what are type types of matelloproteinases, what do they do |
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Definition
stromelysins: break down proteoglycans, laminin, fibronectin
collagenases: break down collagen |
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Term
| what are two types of abberations |
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Definition
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Term
| what is the cause of a kypertrophic scar |
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Definition
normal wound healing progresses to excessive accumulation of type I collagen
PGDF may have a role |
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Term
| what is the cause of a keloid |
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Definition
scar tissue (type III collagen) grows beyond the boundries of a wound
keyloid fibroblasts have increased response to PDGF so this may be the cause |
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Term
| what are the six steps in wound healing |
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Definition
1. acute inflammation
2. parenchymal cell regeneration if possible
3. migration and proliferation of parenchymal cells and CT
4. synthesis of ECM
5. remodeling parenchymal elements to restore tissue function
6. remodeling of CT to achieve wound strength |
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Term
| primary goals of wound healing |
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Definition
heal focal disruption of epithelial cells
clean, disinfect
epithelial regeneration predominates over fibroblasts |
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Term
| secondary goal of wound healing |
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Definition
cell or tissue loss like ulcers, abscesses, or large wounds form granulation tissue
ECM accumulation and scaring |
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Term
| what are the differences between the primary and secondary goals of wound healing |
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Definition
secondary has
more intense inflammatory reactions: more necrosis, debris, exudate, fibrin
larger granulation tissue: fills gaps, provides framework
wound contraction: myofibrills contract and wound shrinks by 5-10% in 6 weeks |
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Term
| first intention wound: aka, describe it, what are the main goals in healing this would |
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Definition
primary union
the edges of the wound line up well and the primay goals of healing are to disingect, clean, and regenerate epithelium (rather than insert fibrous tissue) |
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Term
| secondary intention wound: aka, describt it, what are the main goals of healing in this woumd |
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Definition
secondary union
large gaps between wound edges
primary goal of healing is extension of granulation, ECM, scars, wound contraction |
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Term
| in one week how strong is scar tissue? how long does it take for it to reach full strength, how strong is this? |
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Definition
10% strength in a week
70-80% max strength in 3 mo |
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Term
| how is scar tissue strengthed (3) |
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Definition
collagen degredation and synthesis
switching from collagen III to collagen I
extracellular cross linking of collagen |
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Term
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Definition
| wound fails to heal in closed position |
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Term
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Definition
excessive tension on the wound leads to necrosis, decreased strength
electronic coagulation increases inflammatory response to necrotic tissue
removal of suturues to early
infection
trauma |
|
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Term
| what are risk factors for wound dehisence (5) |
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Definition
>65 yo
hypoalbumenia
tobacco
corticosteroids
systemic infection |
|
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Term
| list some disorders that cause issues with inflammation and repair (5) and breifly describe them |
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Definition
leukocyte adhesion deficiency: integrin deficiency causes problems with chemotaxis
chronic granulamatous disease: NADPH oxidase deficiency causes problem with killing bacteria and infection is the most important delay in wound healing
keloids: type III collagen overgrowth and no transformation to type I
vitamin C deficiency: hinders collagen synthesis
corticosteroids |
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Term
| explain the role of fibrosis formation in chronic inflammation |
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Definition
continous stimulus keeps activating macrophages and leukocytes to release growth factor and cytokines to increase collagen and decrease metaloproteinase activity which causes fibrosis
people who have chronic inflammation are often on seroids and this decreases metaloproteinase activity too |
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