Wound Healing Flashcards
1
Q
what is wound healing?
A
replacement of destroyed tissue by living tissue
2
Q
stages of wound healing
A
- bleeding
- inflammatory
- proliferation
- remodelling
3
Q
wound healing
stage 1 - haemostasis
A
- constriction of damaged blood vessels
- formation of blood clot
- platelets aggregate at site of injury
- activation of intrinsic + extrinsic clotting pathways
- formation of initial fibrin matrix
4
Q
wound healing
stage 2 - inflammation
A
- recruitment of inflammatory cells by chemo-attractants
- neutrophils remove dead tissue prevent infection
- macrophages + monocytes clean by phagocytosis and release growth factors
- lymphocytes arrive in large numbers
5
Q
stage 3 - proliferation - granulation tissue forms
A
- macrophages release cytokines that attract fibroblasts and lymphocytes
- PDGF, EGF, TGF, IL-1 instruct mesenchymal stromal cells to make various structures
- fibroblasts make new connective cells
- initial fibrin matrix replaced by type 3 collagen
6
Q
stage 3 - proliferation - angiogenesis
A
- stimulated by areas of high lactate, high acid & low oxygen
- EGF-1 most potent angiogenic stimulant
- Heparin is a cofactor
- TGF-alpha, TGF-beta & prostoglandins encourage angiogenesis
7
Q
stage 3 - proliferation - contraction of wound edges
A
- begins after 4-5 days
- movement is centripetal
- max contraction lasts 2 weeks - approx 0.7mm/ day
- fastest contraction on lax tissues
- square wound faster than round
8
Q
stage 3 - proliferation - epithelialisation
A
- provisional basement membrane includes - fibronectin , collagen type 1 & 3
- epithelial cells proliferate
- contact inhibition chemicals release when edges come together
9
Q
stage 4 - remodelling
A
- maturation and organisation scar tissue
- collagen formation for tensile strength
- number of intermolecular cross links b/w fibres increases dramaticallu
- type 3 collagen replaced by type 1
- neat scar changes from red to white
10
Q
wound healing
platelet derived growth factor
A
- promotes migration + proliferation of fibroblasts
- chemotactic for monocytes
11
Q
wound healing
epidermal growth factor
A
promotes growth of :
* endothelial cells
* epithelial cells
* fibroblasts
12
Q
wound healing
fibroblast growth factor
A
- synthesis of ECM proteins
- promotes angiogenesis
- chemotactic for fibroblasts
13
Q
wound healing
vascular endothelial growth factor
A
promotes angiogenesis
14
Q
wound healing
systematic factors
A
- nutrition
- metabolic health
- circulatory status
15
Q
local factors
A
- presence of infection
- foreign material
- motion
