Wound Healing Flashcards
What is the difference between parenchyma and stroma?
Parenchyma is functional and stroma is structural.
What is the definition of labile cells?
These are constantly dividing. Examples include surface epithelium.
What is the definition of stable cells?
They only divide when necessary. Examples include parenchymal cells of liver, pancreas and kidney.
What is the definition of permanent cells?
These cells never divide. Examples include neurons, skeletal and cardiac muscles.
Is a mesenchymal cells stable, labile of permanent?
Stable
Is vascular endothelium stable, labile of permanent?
Stable
What two phases are involved in the formation of granulation tissue?
Angiogenesis and fibrogenesis.
Describe how angiogenesis occurs from pre-existing vessels
There is vasodilation mediated by nitric oxide and increases permeability mediated by VEGF. The basement membrane will be destroyed by MMPs and the endothelial cells will then migrate to the stimuli and begin to proliferate.
Describe how angiogenesis occurs from stem cells
The cells are derived from endothelial precursor cells and are found in bone marrow. They will migrate to area
What is the meaning of MMPs?
Matrix metalloproteinase
What is the three stages of wound healing and what are their time lengths?
Inflammation: 6-8 hours
Proliferation: 5-7 weeks
Maturation: Weeks
What is the meaning of healing by first intention?
This is where there is a clean cut wound, no infection and there is a limited amount of tissue loss.
What is the role of the blood clot that forms within the first stage of wound healing?
To seal the wound to prevent it from infection and dehydration, stop bleeding and act as a scaffold.
During inflammation, what is the first cell to appear?
Neutrophils: within 24 hours
When do fibroblasts start to proliferate?
24-72 hours
What are some factors that are responsible from fibroblast migration?
PDGF, TNF, FGF
What cell eventually replace neutrophils?
Macrophages
Fibroblasts will initially lay down a provisional matrix. What are the components of this?
Collagen III, fibrin and fibronectin
What will the provisional matrix be replaced with?
Type three collagen
What happens during maturation?
There will be very little inflammatory cells and re-vascularisation. The granulation tissue will be replaced with dense collagen material to form scar tissue.
What cells carry out contraction of the wound?
Myofibroblasts: these are intermediate cells between smooth muslces cells and fibroblasts.
what percentage of the original strength is achieved by week 3 during wound healing?
70-80%
What is healing by secondary intention?
There is not a clean cut, large size, infection and a large amount of tissue loss.
What are some factors that affect wound healing?
Protein malnutrition, vitamin C deficiency , Glucocorticoids, infection, presence of foreign substance, areas with poor blood supply (eg foot)
