Podcast
Questions and Answers
How does repair by fibrosis differ fundamentally from regeneration?
How does repair by fibrosis differ fundamentally from regeneration?
- Fibrosis replaces damaged tissue with granulation tissue, leading to scar formation and potential functional impairment. (correct)
- Regeneration only occurs in tissues composed of permanent cells, such as muscle and nerve cells.
- Fibrosis involves replacement with cells of the same type, maintaining original tissue function.
- Regeneration results in the formation of granulation tissue, which matures into a scar.
Which statement accurately contrasts wound healing by primary and secondary intention?
Which statement accurately contrasts wound healing by primary and secondary intention?
- Secondary intention primarily results in faster epithelization compared to primary intention, irrespective of the wound gap.
- Primary intention healing involves gaping wounds with marked tissue destruction, while secondary intention occurs in clean surgical wounds.
- Secondary intention relies on minimal bleeding and bacterial infection, whereas primary intention involves greater inflammatory response.
- Primary intention demonstrates lower liability to infections and complications in comparison to secondary intention. (correct)
In the context of tissue repair, what is the primary role of macrophages during early granulation tissue formation?
In the context of tissue repair, what is the primary role of macrophages during early granulation tissue formation?
- Replacing polymorphonuclear leukocytes (PNLs) and stimulating fibroblast and angioblast in-growth. (correct)
- Initiating the process of neovascularization to fill the wound gap.
- Sealing off the defect by forming an epidermal bridge.
- Directly depositing collagen type III to form the initial scar matrix.
How do labile cells contribute to the repair process, and which characteristic primarily defines their role?
How do labile cells contribute to the repair process, and which characteristic primarily defines their role?
What is the role of fibroblasts within granulation tissue, and how does this relate to the eventual outcome of tissue repair?
What is the role of fibroblasts within granulation tissue, and how does this relate to the eventual outcome of tissue repair?
Which of the following statements accurately describes the characteristics of granulation tissue?
Which of the following statements accurately describes the characteristics of granulation tissue?
How do systemic factors like chronic debilitating diseases and diabetes affect wound healing?
How do systemic factors like chronic debilitating diseases and diabetes affect wound healing?
What is the significance of collagen type III in the context of wound healing and scar formation?
What is the significance of collagen type III in the context of wound healing and scar formation?
How do steroids and cytotoxic drugs impact the process of tissue repair, and what mechanisms are involved?
How do steroids and cytotoxic drugs impact the process of tissue repair, and what mechanisms are involved?
Considering the complications of wound healing, how does a sinus differ from a fistula?
Considering the complications of wound healing, how does a sinus differ from a fistula?
What distinguishes permanent cells from stable cells in terms of their proliferative capacity following tissue damage?
What distinguishes permanent cells from stable cells in terms of their proliferative capacity following tissue damage?
How does the process of neovascularization contribute to the formation of fully developed granulation tissue?
How does the process of neovascularization contribute to the formation of fully developed granulation tissue?
Which of the following factors primarily dictates whether a tissue undergoes regeneration or repair by fibrosis after injury?
Which of the following factors primarily dictates whether a tissue undergoes regeneration or repair by fibrosis after injury?
Following the initial hemorrhage in a wound undergoing healing by primary intention, what is the immediate subsequent event and its major purpose?
Following the initial hemorrhage in a wound undergoing healing by primary intention, what is the immediate subsequent event and its major purpose?
How does the size and site of a wound act as a local factor affecting wound healing?
How does the size and site of a wound act as a local factor affecting wound healing?
During the remodeling phase of scar formation, what is the predominant activity that determines the long-term structural integrity of the healed tissue?
During the remodeling phase of scar formation, what is the predominant activity that determines the long-term structural integrity of the healed tissue?
What is the primary consequence of excessive collagen deposition during the repair process?
What is the primary consequence of excessive collagen deposition during the repair process?
How do nutritional disorders, such as anemia and malnutrition, specifically delay the tissue repair process?
How do nutritional disorders, such as anemia and malnutrition, specifically delay the tissue repair process?
Under what conditions would healing by secondary intention be the most likely outcome?
Under what conditions would healing by secondary intention be the most likely outcome?
In the context of wound healing, what role do epithelial cells play during the epithelial changes phase (approximately 48 hours after injury) in healing by primary intention?
In the context of wound healing, what role do epithelial cells play during the epithelial changes phase (approximately 48 hours after injury) in healing by primary intention?
Flashcards
Repair
Repair
Replacement of damaged tissue by living tissue.
Regeneration
Regeneration
Replacement of destroyed tissue by the same cells.
Labile cells
Labile cells
Cells with a good power of continuous proliferation to replace aging cells.
Stable cells
Stable cells
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Permanent cells
Permanent cells
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Repair by fibrosis
Repair by fibrosis
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Granulation tissue
Granulation tissue
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Healing by Primary Intention
Healing by Primary Intention
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Healing by Secondary Intention
Healing by Secondary Intention
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Sinus (wound healing)
Sinus (wound healing)
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Fistula (wound healing)
Fistula (wound healing)
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Ulcer (wound healing)
Ulcer (wound healing)
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Keloid (wound healing)
Keloid (wound healing)
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Cicatrization (wound healing)
Cicatrization (wound healing)
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Local Factors Affecting Wound Healing
Local Factors Affecting Wound Healing
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Systemic Factors Affecting Wound Healing
Systemic Factors Affecting Wound Healing
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Study Notes
- Repair is the replacement of damaged tissue by living tissue
Types of Repair
- Regeneration is the replacement of destroyed tissue by the same cells, for example, bone fracture repair
- Repair by fibrosis is the replacement of destroyed tissue by granulation tissue, which matures into fibrosis
Cell Proliferation Capacity
- Cells are classified based on their proliferative capacity: labile, stable, and permanent
- Labile cells have a high capacity for continuous proliferation to replace aging cells
- Examples of labile cells include stratified squamous epithelium of the skin and columnar epithelium of the gastrointestinal tract
- Stable cells do not proliferate under normal conditions but can proliferate when needed
- Parenchymatous cells like those in the liver, pancreas, and renal tubules, as well as mesenchymal cells like fibroblasts, chondroblasts, and osteoblasts, are examples of stable cells
- Permanent cells cannot proliferate; muscle cells and nerve cells are examples
Granulation Tissue
- Granulation tissue is red, granular, soft, painless, and bleeds easily; it forms in the gap of healing wounds
- It consists of fibroblasts surrounded by collagen, newly formed blood vessels, scattered macrophages, and some inflammatory cells
- Scar formation occurs after excess collagen deposition and obliteration of the capillaries
Characteristics of Granulation Tissue
- It appears light red or dark pink due to perfusion with new capillary loops
- It is soft to the touch
- It has a moist, granular appearance due to punctate hemorrhages
- It is pulsatile on palpation and painless when healthy
Wound Healing by Primary Intention
- Healing occurs in clean surgical wounds with minimal tissue destruction, minimal bleeding, and no bacterial infection, with good apposition of wound edges
Steps of Healing by Primary Intention
- Initial hemorrhage fills the wound cavity with a blood clot
- Inflammation occurs within 24 hours as polymorphonuclear leukocytes (PNLs) infiltrate the blood clot
- Epithelial changes occur within 48 hours as epithelial cells from wound edges proliferate
- Early granulation tissue forms on the third day as macrophages replace PNLs
- Macrophages stimulate the ingrowth of fibroblasts and angioblasts, which start forming collagen type III
- Epidermal cells form a bridge that seals off the defect
- Fully developed granulation tissue appears by days 4–6, with neovascularization
- Granulation tissue fills the wound gap
- Scar formation occurs in the second week as inflammation subsides, and fibroblastic proliferation and collagen deposition continue
- Remodeling of the scar occurs by the end of the first month
Healing by Secondary Intention
- This occurs in gaping wounds with marked tissue destruction, bleeding, infection, and poor apposition of wound edges
- Healing shares the same steps as primary intention, but the inflammatory response is greater, and there is abundant granulation tissue formation
- Epithelization takes longer, depending on the wound gap
- Excessive fibrosis and wound contraction occur
- There is more liability to infection and complications
Factors Affecting Wound Healing
- Local factors include the size and site of the wound, infection, foreign bodies, and poor blood supply to the area
- Systemic factors include age, nutritional disorders like anemia and malnutrition, metabolic disorders, chronic debilitating diseases, diabetes, and drugs like steroids and cytotoxic drugs
Complications of Wound Healing
- Infection
- Sinus formation: a blind duct lined by epithelium between the wound and external surface
- Fistula formation: a duct lined by epithelium between the wound and a hollow organ
- Ulcer: loss of continuity of surface epithelium
- Keloid: excessive granulation tissue and scar formation
- Incisional hernia
- Cicatrization: scars on flexures interfere with movement
- Implantation (epidermal) cyst
- Malignant transformation: squamous cell carcinoma
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