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PA: Healing
| Question | Answer |
|---|---|
| What is regeneration? | Restoring tissue; new tissue is IDENTICAL to old tissue in structure and function |
| What is repair? | Fibrous scar formation; normal structure, BUT function is altered |
| What is ideal healing? | New tissue identical to old |
| What is acceptable healing? | Almost normal structure, but less than optimal function |
| What is minimal healing? | Minimal normal structure and partial function |
| What is failed healing? | Abnormal structure and function |
| What is an example of failed healing? | Articular cartilage (once it's gone, it's gone) |
| What are the four key successive phases of healing? | Hemostasis Inflammatory Proliferative Remodeling/maturation |
| What is the hemostasis phase? | Stopping of bleeding, body's emergency response to form blood clots, lasts seconds to minutes, may form hematoma |
| What is the inflammatory phase? | Wound cleaned of debris |
| What are the 5 signs of inflammation? | Redness Swelling Increased temperature Pain/tenderness LOF |
| What are the two categories of the proliferative phase? | Fibroplasia Angiogenesis |
| What is fibroplasia? | Formation of new scar tissue |
| What is angiogenesis? | Formation of new blood vessels |
| What is the remodeling/maturation phase? | Fibers align correctly and increase in strength (~300 days) |
| What is the initial response after injury? | Vasoconstriction followed by vasodilation |
| What are some positive edema consequences? | Dilute harmful substances Bring in O2 and other nutrients Lets clotting proteins in |
| What are some negative edema consequences? | Compression in the vicinity, which then pushes on nerves eliciting pain Compression further disallow venous and lymphatic drainage |
| What is margination? | Leukocytes come in contact with endothelium and adheres to it |
| What is diapedesis? | Passage of leukocytes through capillary walls |
| What is chemotaxis? | Calling neutrophils to the area |
| When do neutrophils arrive after an injury? | Appear within one hour of injury, secondary to injured cells releasing leukocytosis inducing factors |
| When do monocytes appear? | 2-4 days after injury |
| What do monocytes transform into? | Dendritic cells and macrophages |
| What do macrophages do? | Remove dead cells and debris |
| When do lymphocytes appear? | ~5 days post injury |
| What is different about chronic inflammation compared to acute inflammation? | Chronic inflammation does not present with the cardinal signs of inflammation |
| What are 4 important things regarding inflammatory chemicals | Histamine Kinin Prostagladin Complement system |
| What does histamine do? | Vasodilation Increases capillary permeability |
| What do kinins do? | Vasodilation Major pain causing chemicals |
| What do prostagladins do? | Sends danger message |
| What does the complement system do? | Enhances defense |
| What are the components of repair phase of wound healing? | Granulation Fibroplasia Angiogenesis Re-epithelialization |
| What does granulation tissue do? | Reduced edema |
| What type of tissue is indicative of normal healing? | Granulation tissue |
| How soon does type III collagen start forming after an injury? | 2 days |
| What type of collagen (I or III) is unorganized and has poor strength? | Collagen (Type III) |
| What are the three stages of the remodeling phase? | Collagen conversion Wound contraction Scar formation |
| What is the tissue breaking strength when compared to pre-wound values? | Never throught to exceed 80% |
| What is necessary for collagen cross-linking to occur? | Oxygen |
| What is wound contraction? | Process that closes wound after tissue loss |
| What are the main effector cells for wound contraction? | Myofibroblasts |
| What is scar formation associated with? | Wound contraction |
| How many stages make up scar formation? | 4 stages |
| Characteristics of Stage I of scar formation | 2-4 days post injury Type III collagen Prone to tear |
| Characteristics of Stage II of scar formation | 5-21 days post injury Type III converted to type I collagen Less likely to tear MOST receptive to intervention |
| Characteristics of Stage III of scar formation | 21-60 days post injury More fibrous and strong Decreased response to intervention |
| Characteristics of Stage IV of scar formation | 60 days post injury Scar maturation Final appearance Unresponsive to treatment, surgical intervention considered |
| What is the difference between hypertrophic and keloid scars? | Hypertrophic scars do not extend outside of the wound bed Keloid scars typically extend outside of the wound bed and are typically seen in Asian and African populations |