Wound Healing Flashcards
Efferocytosis
Process by which phagocytic cells (e.g. macrophages) engulf and remove apoptotic (dying) cells.
This is what causes tattoo spreading
Foreign body giant cells (FBGCs)
Large, multinucleated cells formed by the fusion of macrophages in response to a large, persistent foreign material that cannot be easily phagocytosed (e.g. splinter, implant).
Granuloma
Organized cluster of immune cells that forms around a chronic infection or foreign body that cannot be eliminated (macrophages, FBGCs, connective tissue, etc).
What causes stretch marks?
Tearing of the connective tissue in the dermis due to rapid stretching of the skin that exceeds its elastic limit.
4 stages of wound healing
- Hemostasis
- Inflammation
- Cell proliferation and matrix production
- Remodelling
Sequence of cell proliferation after injury
- Neutrophils
- Macrophages
- Fibroblasts
- Lymphocytes
Sequence of matrix protein proliferation after injury
- Fibronectin & collagen III (quick fix)
- Collagen I (long-term fix)
What promotes healing of the tissue after clot formation?
The clot seals the wound and stops bleeding. However, it also promotes healing via the release of growth factor from platelets and surrounding cells.
Key growth factors involved in wound healing
TGF-beta!!!
PDGF
EGF
FGF
Granulation tissue
New connective tissue and microscopic blood vessels that form on the surface of a wound during the healing process (eventually gets covered by epidermis).
By what process are the edges of a wound pulled together ?
Contraction by myofibroblasts (actin-mediated)
Enzymes responsible for ECM remodelling
Matrix metalloproteinases (MMPs)
Define dermal fibroses
Excessive scarring and thickening of the skin due to overactive healing response and overproduction of collagen (fibrosis) in the dermis.
* Prolonged inflammatory response leads to increased and sustained ECM production.
* Fibroblasts have more GF receptors and respond more readily to TGF-beta.
2 types of dermal fibroses
Hypertrophic scars
Keloids
Hypertrophic scars (key features)
Thick raised scars due to abnormal wound healing. Stay within the confines of the wound.
Keloids (key features)
Thick raised scar due to abnormal wound healing. Grow beyond the wound margin (invasive).
Scleroderma (definition + cause)
Group of autoimmune diseases that result in the hardening and tightening of the skin.
It is caused by excessive collagen production.
