2-Wound Healing Flashcards
wound healing
definition
complete restoration of og architecture and function of tissue or anatomic part after an injury
-regeneration
wound repair is not fully recovery just functional compromise
phases of healing process
- inflammatory
- proliferative
- remodeling
inflammatory phase
up to 3 days after wound
-platelets, neutros, macros
-clot formation + inc vessel perm so neturos migrate into tissue + macros clear debris
proliferative phase
day 3- weeks later
-fibroblasts, myofibros, endothelial cells, keratinocytes, macros
-granulation tissue and collagen III deposition
-angiogenesis/epi cell prolif, clot dissolution, wound contraction by myofibros
if vit C or copper def then delay healing
remodeling phase
starts early as 1 week-6+ months
-fibroblasts
-collagen III replaced by type I to inc strength of tissue
delay if zinc deficiency
macrophage functions
- removal of injured tissue- phagocytosis
- antimicrobial activity- mitric acid, ROS
- chemotaxis + prolif of fibros - TGF-beta, IL-1, TNF
- angiogenesis- VEGF, PDGF
- deposition/remodel of ECM- TGF-beta, PDGF, TNF, IL-1,
PDGF
secreted by activated platelets and macros
-induce vascular remodel and smooth muscle cell migration
-stims fibros growth for collagen syn
FGF
stims angiogenesis by promote prolif of endo cells
-also stims prolif of fibros
EGF
stims cell growth via tyrosine kinases
-EGFR, ErbB1
metalloproteinases
tissue remodelling
VEGF
stims angiogenesis
angiogenesis
capillary budding
-endo cells prolif to form new vessel
reg by VEGF
fibrogenesis
fibroblast activatin and prolif
-deposits collagen
stim by TGF-beta
granulation tissue
3-5 days later granulation tissue is apparent
-pink, soft, granular appearance
-progressively acc CT matrix via cicatrization so dense fibrosis scarring
-only temporary
histologic appearance granulation tissue
- prolif of fibroblasts surrounded by abundant ECM
- new thin walled delicate capillaries
- fibros and capillaries in loose ECM
- scattered macros + other inflamm cells, if early stage then numerous macros, myofibros, vessels
-late stage is less vascular, more matrix and fibros
cicatrization
combo of collagen depo + contraction + devascularization to form scar
-contraction could lead to deformity and functional impairment (contracture)
-more gran tissue = more contraction > inc risk of organ impairment
factors influence tissue repair
- infection-delays healing
- diabetes-abnormal healing
- steroids- weakness of scar bc inhibits TGF-b so fibros diminished
- ischemia- from arteriosclerosis, diabetes, obstructed venous drain
- foregin body- steel, glass, bone
- nutritional status- protein def, vit C def,
first intention healing
closed, non-infected wound
-margins are opposed, healing occurs directly with minimum gran tissue
-epithelial regen (epithelization) predoms fibrosis
second intention healing
-wound margins are non-opposed aka too separated
-large tissue defects more necrotic debris so more exudate/fibrin need removal
-more gran tissue formed
-large gaping, infection, foreign body wounds
-too many myofibros = contraction within 6 wks
contracture
exaggeration of contraction
reduction in size of wound via second intention bc exposed surface dec by gradual regen of surface epi
-severe deformity, limit joint mobility
usually with burns or hollow viscera (male urethra, esoph, intestine) > stenosis
myofibroblasts can produce collagen and contract so hybrid properties
keloid
acc of exuberant amount of collagen I and III so prominent raised scars, lack glands and hair follicles
-hereditary predis african americans
-disorganized structure
-extends borders
-few myofibros
hypotrophic scars
atrophic, depressed/sunken
hyperpigmented appearnace bc loss of collagen and ground substance
-acne, stretch marks
hypertrophic scars
structurally similar to keloid but not progress beyond 6 mo and not recur after excision
-inc in type III collagen in parallel organization
-stays confined to borders of og scar
-numerous myofibros
-no predis
proud flesh
xs gran tissue, abnormal cell growth and ECM prod in wound healing
-will protrude above skin so prevent closure and hinder epithelization
-bleed excessively if traumatized
-must cauterize or surgery
