14 Wound Healing Flashcards
what are the phases of wound healing?
inflammation, proliferation, remodeling
how long dose inflammation last?
1-10d
what happens during inflammation?
pmns, macrophages, epithelialization
how fast does epithelialization work?
1-2mm/d
how long does proliferation last?
5d-3weeks
what happens during proliferation?
fibroblasts, collagen deposition, neovascularization, granulation tissue formation, type III collagen replaced w type I
how long does remodeling last?
3w to 1 yr
what happens to vascularity during remodeling?
decreased vascularity
what happens during remodeling?
collagen cross-linking occurs
does the amount of collagen increase or stay the same during remodeling?
net amount doesn’t change but significant production and degradation occur
how fast do peripheral nerves regenerate?
1mm/d
what is the order of cell arrival in a wound?
platelets, PMNs, macrophages, lymphocytes, fibroblasts
illustrate timeline of phases of wound healing with dominant cell types and major physiologic events
http://cl.ly/image/1R0L3o3L3a0Y
what do macrophages do?
essential for wound healing: release growth factors, cytokines, etc.
what does fibronectin do?
chemotactic for macrophages; anchors fibroblasts
what do fibroblasts do?
replace fibronectin-fibrin with collagen
list the prominent cell type by day.
day 0-2: PMNs
days 3-4: macrophages
days 5 and on: fibroblasts
what is a platelet plug consisted of?
platelets and fibrin
what does a provisional matrix consist of?
platelets, fibrin, fibronectin
what is accelerated wound healing?
reopening a wound results in quicker healing the 2nd time (as healing cells are already present there)
what is the most important factor in healing open wounds (secondary intention)
epithelial integrity
what happens to epithelial cells on the skin near open wounds?
epithelial cells migrate from hair follicles (#1 site), wound edges, and sweat glands
what is epithelial integrity dependent on?
granulation tissue in wound
what happens to unepithelialized wounds?
leak serum, protein, promote bacteria
what is the most important factor in healing closed incisions (primary intention)?
tensile strength
what does tensile strength depend on?
collagen deposition and cross-linking of collagen
what is the strength layer of bowel?
submucosa
when is the weakest time point for small bowel anastomosis?
3-5d
how do myofibroblasts communicate?
gap junctions
what are myofibroblasts called in the smooth muscle cell?
fibroblast
what do myofibroblasts do?
involved in wound contraction and healing by secondary intention
what has better wound contraction: perineum or leg?
perineum
what is the most common type of collagen?
I
what is the primary collagen in a healed wound?
I
what type of tissue is type I collagen?
skin, bone, tendons
what type of tissue is type II collagen
cartilage
what collagen type is increased in a healing wound?
III
what type of collagen is in blood vessels and skin?
III
what type of collagen makes up basement membranes?
IV