Critical phase of healing Flashcards
What is tissue healing?
Innate mechanism residing in healthy tissue
Examples of excessive healing
Scleroderma
Keloid scarring
Examples of impaired healing
Diabetes
Vitamin C deficiency
What governs tissue healing?
Genetic factors.
Mechanism is embedded in our tissues since birth
What are the 3 stages of tissue healing?
Inflammatory stage (4-6) Proliferative stage (2-24) Remofelling stage (21-2 years)
What happens in the inflammatory stage?
Swelling and warmth around the wound
Inflammatory mediators go to the wound
What happens in the proliferative stage?
New blood vessels grow through the wound
Fibroblasts first lay down ECM to close wound
The fibroblasts then fully differentiate into myofibroblasts that lay donw new connective tissue and fully repair the wound site
What happens during the remodelling stage?
Tissue is normalised
Inflammation subsides
Tissue is repaired
What releases growth factors that promote wound healing during the inflammatory process?
Clots
What are some of the growth factors released by clots that promote wound healing?
TGF-b and PDGF
How does the epithelial layer respond in response to these growth factors?
Proliferates and divides to cover wound
How does expression of the collagen gene change during repair process?
Highest expression in day 7
Lower in the beginning
Main protein in ECM
What is the role of PGE2?
Dilates and makes blood vessels more leaky
When is PGE2 maximally expressed?
Early in the wound repair process
Why is wound healing important clinically?
Non-healing wounds is a common and costly medical problem
No effective treatment for excessive wound healing or non-healing pathologies
