Wound Healing Flashcards
List the 4 stages of wound healing
Haemostasis
Inflammation
Proliferation
Remodelling
Signs of inflammation
Pain
Swelling
Heat
Loss of function
List 2 phases of acute inflammation
Vascular
Cellular
Function of vascular acute inflammation
Prevent further injury, dilutes toxins & bacteria
Approximate time scale for vascular acute inflammation
Almost immediate - 3/5 days
what causes mast cells to burst
damaged tissue
what causes vasodilation in wound healing
histamine
when mast cells burst what do they release
histamine, serotonin
what causes stimulation of pain receptors
pressure from swelling
What 2 functions does platelets, histamines and serotonin have in wound healing
Causes vasodilation (heat/redness)
Increased vascular permeability (swelling/pain)
how does proteins and plasma move into intracellular spaces
osmosis
what sensitises pain receptors
bradykinin and prostaglandins
what does vasodilation do
increase blood flow
what happens when endothelial cells lose their tight junctions
blood vessels become leaky - increased permeability
when does the area become hypotoxic
when blood supply has been lost in the injury
what does histamine stimulate
endothelial cells to lose their tight junctions
After 12 - 24 hours which phase starts
Cellular
Functions of cellular acute inflammation
Removes bacteria, cleans up tissue and prepares for wound repair
Identify the cells involved in cellular inflammation
Neutrophils
Macrophages
explain the role of macrophages at end of inflammation
they release proinflammatory cytokines or anti inflammatory cytokines and growth factors that progress the wound
What is angiogenesis
New blood vessel growth
What is the function of neutrophils in wound healing
Phagocyte - Bacterial destruction and clean up
What is the function of macrophages in wound healing
Phagocyte - bacterial clean up, damaged tissue removal and dead neutrophils, release growth factors
How do neutrophils die
Apoptosis
What is apoptosis
When neutrophils fill their self up with bacteria
What is a monocyte
Immature macrophages
What are the 5 stages of how cells travel from the blood to the site of injury (cellular phase)
Margination
Rolling / pavementing
Adhesion
Diapedesis
Chemotaxis
Explain margination
As blood flow becomes congested, phagocytes drop the margins
explain rolling / pavementing
weak attraction and rolling along the endothelial cells
explain adhesion
phagocytes attaches strongly to special attachment proteins
explain diapedesis
phagocyte squeezes through leaky membrane into intracellular spaces
explain chemotaxis
cells move to area of damage following cytokine concentration gradient, cell debris
describe what happens to epithelial cells in early proliferation
loss of contact stimulates epithelial cells to replicate
macrophages release growth factors
epithelial cells replicate
how do epithelial cells replicate
leap frog over each other
process repeats until they meet in the middle
describe the role of fibroblasts in early proliferation
fibroblasts migrate into the wound
they make ground substance and type 3 collagen
what characteristic does type 3 collagen have compared to type 1
it is much weaker
less organised
easily broken
explain how blood vessels grow into the wound during early proliferation
fibroblasts and epithelial tissue quickly use up local oxygen levels
m2 macrophages release growth factors
this stimulates endothelial cells of blood vessels to replicate
which direction does endothelial cells grow
towards hypotoxic areas
which tissue is present at the end of proliferation
granulation
list the components of granulation tissue
fibroblasts
ground substance (proteoglycans)
type 3 collagen
macrophages
new blood vessels
new epithelial tissue
when does a fibroblast make smooth muscle actin (myofibroblasts)
when physical stress on the new tissue stimulates the fibroblast
what causes reduction in wound size
myofibroblasts attached to collagen bundles and which contracts to pull inwards
what happens at the end of proliferation
epithelial cells have recovered the site
invading blood vessels are now organised
fibroblasts have filled the wound with type 3 collagen and ground substance