21 Questions
Which cells are dominant during the inflammation phase of wound healing?
PMNs
During the proliferation phase of wound healing, which cell type is responsible for depositing collagen and promoting neovascularization?
Fibroblasts
What is the predominant cell type involved in the remodeling phase of wound healing?
Fibroblasts
Which growth factor is associated with the inflammation phase of wound healing?
TNF-alpha
What occurs during the proliferation phase of wound healing?
Neovascularization
What is the net change in the amount of collagen during the remodeling phase of wound healing?
No change
Which cell type is responsible for depositing collagen during wound healing?
Fibroblasts
What is the primary function of macrophages during wound healing?
Release growth factors and cytokines
Which phase of wound healing involves epithelialization at a rate of 1-2 mm/day?
Proliferation
What is the order of arrival of cells in a wound according to recent research?
PMNs, Platelets, Macrophages, Lymphocytes, Fibroblasts
What is the rate of peripheral nerve regeneration during wound healing?
1 mm/day
Which cell type is responsible for releasing TNF-alpha and IL-1 during the inflammation phase of wound healing?
PMNs
What type of protein is produced by fibroblasts and is chemotactic for macrophages?
Fibronectin
During which phase of wound healing is the platelet plug formed?
Hemostasis phase
Which factor is most important for closed incisions and is dependent on collagen deposition and cross-linking?
Tensile strength
Which vitamin deficiency can lead to scurvy, impairing wound healing?
Vitamin C
Which type of collagen is the most common in a healed wound?
Type I
What is the crucial component for open wound healing (secondary intention)?
Epithelial integrity
Which type of granules in platelets contain coagulation factors, PDGF, and TGF-beta?
Alpha granules
What type of suture closure may prevent infection?
Primary intention closure
Which cells are involved in wound contraction and healing by secondary intention?
Myofibroblasts
Study Notes
- Fibronectin: protein produced by fibroblasts, chemotypeic for macrophages, anchors fibroblasts in the provisional matrix (mostly fibronectin and hyaluronic acid)
- Wound healing timeline: Days 0-2 dominated by PMNs, Days 3-4 by macrophages, Days 5 and on by fibroblasts
- Platelet plug: formed by platelets and fibrin during the hemostasis phase
- Epithelial integrity is crucial for open wound healing (secondary intention)
- Granulation tissue formation and secretion of proteins like collagen essential for wound healing
- Unepithelialized wounds can leak proteins and promote bacteria
- Tensile strength: most important factor for closed incisions (primary intention) dependant on collagen deposition and cross-linking
- Suture removal: 1 week for the face, 2 weeks for other areas, delayed primary closure may prevent infection
- Submucosa: strength layer of bowel, weakest time point for small bowel anastomosis is 3-5 days
- Myofibroblasts: smooth muscle cell–fibroblasts involved in wound contraction and healing by secondary intention communicate via gap junctions
- Collagen: several subtypes, Type I most common (primary collagen in a healed wound), Type III predominant during proliferation, collagen synthesis requires oxygen, vitamin C, zinc, and alpha-ketoglutarate
- Wound healing impairments: bacteria, devitalized tissue, cytotoxic drugs, diabetes, vitamin C deficiency (scurvy), steroids, wound ischemia, and disease-related conditions (e.g., Marfan's syndrome, osteogenesis imperfecta, Ehlers–Danlos syndrome, pyoderma gangrenosum)
- Platelet granules: alpha granules contain coagulation factors, platelet-derived growth factor (PDGF), and transforming growth factor beta (TGF-beta), beta-thrombomodulin binds thrombin, dense granules contain adenosine, serotonin, and calcium
- Platelet aggregation factors: TXA2, thrombin, platelet factor 4.
Test your knowledge of the stages of wound healing, including inflammation, proliferation, and remodeling. Understand the role of various cells and growth factors in each stage, as well as the timeline for tissue repair.
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