Wound Healing Physiology (Normal) 3 Flashcards
How do fibroblasts create the ECM?
Fibroblasts produce granulation tissue to produce the matrix or scaffolding.
Fibroblasts production of collagen and ground substances thrive in cytokines and an acidic, low oxygen wound bed.
How is collagen normally laid down in a cell? strength?
Define remodeling.
How much strength will a mature scar have?
Normally laid down in a disorganized pattern. Scar is weak, poor tensile strength.
Remodeling–collagen is remolded by cross-linking into an organized pattern which increases tensile strength of scar.
75% of original tissue–max.
Myofibroblasts extend and contract like what other cells?
What do these cells do?
The shape of a wound determines what?
Smooth muscle cells
Pull the epidermal layer inward and edges pull in together.
How fast the myofibroblasts can contract to close the wound.
Which will close the fastest etc. ?
Circular
Linear
Square/Rectangle
Linear–rapily
Square and rectangle–moderately
Circle–Slowly
What type of wound heals by contraction from myofibroblasts?
If contraction slows or stops, what may happen?
Secondary-intention
Delayed healing and possible excess bleeding and infection. (isn’t closing)
Define senescence
What happens when fibroblasts become senescent?
Aging
The y lose the ability to produce collagen
Fibronectin in chronic v acute wounds…
Appears to be partially degraded compared to acute wounds. Acute has intact fibronectin.
When abnormal, it inhibits healing.
What does chronic wound fluid do?
Chronic wound fluid is full of proinflammatory cytokines. What do they do?
inhibits proliferation of endothelial cells, keratinocytes, fibroblasts, and cell adhesion (slows down all healing).
proinfl…cytokines increase protease production which increases degradation of protein.
Dead space or Large tissue gaps do what?
How do PTs fix it?
Prolong proliferation because of the large amount of tissue that needs to be resurfaced.
Wounds have a tendancy to stall after a time.
PTs will go into reverse and back it up to inflammation stage in order to progress through the proliferative phase.
Remodeling phase
When does it begin?
When does it end?
Describe range of tensile strength from new scar to mature scar?
As soon as granulation tissue forms on the wound site during proliferative phase.
Lasts 1 - 2 years post injury until scar reaches maturity.
Tensil strength starts 15% to 20% and goes to 80%.
In order to prevent problems with scarring, there has to be a balance between what?
Remodling is usually described at the end of proliferative phase but actually occurs concurrently with what?
Collagen synthesis and Collagen lysis.
formation of granulation tissue.
What is hypergranulation?
What if collagen synthesis is impeded?
What if collagen lysis in impded?
“Proud flesh” Creates a humping of the tissue, this prevents epidermal cell movements against gravity to cover and resurface the wound.
The tensile strength is decreased and wound can breakdown or dehisce after skin integrity is restored.
Proliferation will go unchecked and will result in hypertrophy and keloid scarring.
