Pathology Lecture 4: Wound Healing
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Questions and Answers

Which type of cells cannot be replaced if lost?

  • Connective tissue cells
  • Fibroblasts
  • Striated muscle cells (correct)
  • Epithelial cells

    • What is the first process in wound healing?

  • Collagenization
  • Synthesis of ECM proteins
  • Regeneration of native cells
  • Acute inflammatory response (correct)

    • Which factor does NOT contribute to the capacity of a tissue for regeneration?

  • Availability of oxygen (correct)
  • Proliferative ability
  • Type and severity of damage
  • Degree of damage to stromal framework

    • What is the primary role of growth factors in the healing process?

    <p>Facilitate cell division and proliferation</p> Signup and view all the answers

    Which of the following is a source of growth factors following an injury?

    <p>Lymphocytes</p> Signup and view all the answers

    How much does wound contraction typically reduce the size of the defect?

    <p>70-80%</p> Signup and view all the answers

    What occurs during the remodelling phase of wound healing?

    <p>Formation of scar tissue</p> Signup and view all the answers

    Which of the following processes involves the migration of cells into vacant spaces?

    <p>Regeneration</p> Signup and view all the answers

    What is a key characteristic of permanent cells?

    <p>They cannot proliferate.</p> Signup and view all the answers

    What term describes the replacement of lost tissue by living tissue in the context of wound healing?

    <p>Regeneration</p> Signup and view all the answers

    Which type of wound involves the skin remaining intact but underlying tissues being damaged?

    <p>Closed Wound</p> Signup and view all the answers

    Which type of cell has a normally low level of replication but can undergo rapid division in response to injury?

    <p>Stable Cells</p> Signup and view all the answers

    What characterizes permanent cells in terms of their proliferative capacity?

    <p>Non-dividing nature</p> Signup and view all the answers

    What is a key factor determining whether healing occurs by regeneration or repair?

    <p>Destruction of stromal framework</p> Signup and view all the answers

    Which of the following is NOT an example of a labile cell?

    <p>Smooth muscle cells</p> Signup and view all the answers

    What is the primary outcome of repair during the wound healing process?

    <p>Formation of scar tissue</p> Signup and view all the answers

    What is primarily responsible for wound ulceration in patients with varicose veins?

    <p>Inadequate intrinsic blood supply</p> Signup and view all the answers

    What describes the condition known as an incisional hernia?

    <p>Defect in the abdominal wall leading to intestinal protrusion</p> Signup and view all the answers

    What factor contributes to excessive scar formation during wound healing?

    <p>High levels of type III collagen</p> Signup and view all the answers

    What occurs following the formation of a blood clot in the wound healing process?

    <p>Development of granulation tissue</p> Signup and view all the answers

    Which of the following conditions is associated with trophic or neuropathic ulcers?

    <p>Severe atherosclerosis</p> Signup and view all the answers

    What is indicated by a 'maturation arrest' in the wound healing process?

    <p>High rate of collagen synthesis and cross-links</p> Signup and view all the answers

    What type of tissue forms during the early stages of wound repair?

    <p>Granulation tissue</p> Signup and view all the answers

    In which situation is excessive scarring most commonly observed?

    <p>Burn wounds</p> Signup and view all the answers

    What is the most important role of the blood clot in wound healing?

    <p>Stopping bleeding and serving as a scaffold</p> Signup and view all the answers

    What type of wound healing involves a prominent amount of granulation tissue?

    <p>Secondary union</p> Signup and view all the answers

    What role do macrophages play in tissue repair after neutrophils are largely replaced?

    <p>They clear extracellular debris and promote angiogenesis.</p> Signup and view all the answers

    What is the process that leads to the formation of a scar after a wound heals?

    <p>Accumulation of collagen and regression of vascular channels.</p> Signup and view all the answers

    Which stage of fracture healing involves the formation of a hematoma?

    <p>Stage 1: Hematoma formation.</p> Signup and view all the answers

    What distinguishes woven bone from lamellar bone?

    <p>Woven bone shows irregular arrangement of collagen bundles.</p> Signup and view all the answers

    How does wound contraction contribute to the healing process in large surface wounds?

    <p>It decreases the gap between the dermal edges and reduces wound surface area.</p> Signup and view all the answers

    What characterizes scar tissue?

    <p>It is dense and cellular connective tissue.</p> Signup and view all the answers

    Which factor is most likely to result in slower wound healing?

    <p>A wound with impaired blood supply.</p> Signup and view all the answers

    What is a primary characteristic of healing by second intention?

    <p>Granulation tissue forms and fills the wound.</p> Signup and view all the answers

    What role do myofibroblasts play in wound healing?

    <p>They facilitate wound contraction.</p> Signup and view all the answers

    Which of the following statements about local factors influencing wound healing is true?

    <p>Size, type, and location influence wound healing efficiency.</p> Signup and view all the answers

    What type of tissue predominates in granulation tissue during wound healing?

    <p>New connective tissue.</p> Signup and view all the answers

    What can delay the healing of bed sores in patients?

    <p>Pressure-induced ischemia.</p> Signup and view all the answers

    What condition is most likely to prolong healing due to arterial obstruction?

    <p>Diabetes mellitus.</p> Signup and view all the answers

    How does an intense inflammatory reaction affect wound healing?

    <p>It helps in removing fibrin and necrotic debris.</p> Signup and view all the answers

    In which of the following scenarios would healing likely be the slowest?

    <p>A deep wound over the tibia.</p> Signup and view all the answers

    Study Notes

    Pathology Lecture 4: Wound Healing

    • Wound healing is the body's replacement of destroyed tissue by living tissue.
    • A wound is a breach or defect in intact living tissue accompanied by an inflammatory response.
    • Wounds can be accidental or surgical.

    Types of Wounds

    • Closed Wounds: The skin surface is intact, but underlying tissues are damaged (e.g., contusions, hematomas, Stage 1 Pressure Ulcers).
    • Open Wounds: The skin is split or cracked, exposing underlying tissues to the environment.

    Processes of Wound Healing

    • Regeneration: The replacement of lost tissue by similar tissue types.
    • Repair (healing by scarring): The replacement of lost tissue by granulation tissue, which matures into scar tissue.

    Types of Cells

    • Labile Cells: Found in surface epithelium of GI tract, urinary tract, and skin. Lymphoid and hematopoietic cells are examples. High regeneration potential.
    • Stable Cells: Have a lower level of replication and fewer stem cells. Can undergo rapid division in response to injury (e.g. smooth muscle cells, fibroblasts, osteoblasts, endothelial cells). Good regeneration potential.
    • Permanent Cells: Do not divide (e.g., adult neurons, striated muscle cells, lens cells). Cannot be replaced if lost.

    Objectives of Wound Healing

    • Restoration of an intact epithelial surface.
    • Restoration of tensile strength of sub-epithelial tissue.
    • A complex and orderly process.
    • Involves seven distinct processes:
      • Acute inflammatory response upon injury.
      • Regeneration of native cells of tissue involved.
      • Proliferation and migration of native and connective tissue cells.
      • Synthesis of extracellular matrix (ECM) proteins.
      • Remodelling of connective tissue and parenchymal components.
      • Collagenization and progressive acquisition of wound strength.
      • Contraction.

    Growth Factors

    • Healing processes are mediated by growth factors (low molecular weight polypeptides).
    • Promote cell division and proliferation.

    Sources of Growth Factors

    • Platelets (activated after endothelial damage).
    • Circulating serum growth factors.
    • Macrophages.
    • Lymphocytes recruited to the area of injury.

    Healing by Regeneration

    • Regeneration (generare=bring to life) is the renewal of lost tissue with replacement by identical cells.
    • Involves two processes:
      • Proliferation of surviving cells to replace lost tissue.
      • Migration of surviving cells into the vacant space.

    Factors Affecting Wound Healing

    • Local Factors:

      • Wound type (clean, aseptic, blunt trauma).
      • Wound size and location.
      • Vascular supply.
      • Infection.
      • Movement.
      • Ionizing radiation.

    • Systemic Factors:

      • Circulatory status (cardiovascular, blood supply).
      • Infection.
      • Metabolic status (e.g., poorly controlled diabetes).
      • Nutritional deficiencies (e.g., protein, vitamin, trace element).
      • Anti-inflammatory drugs

    Patterns of Wound Healing

    • Healing by First Intention (Primary Union): Clean uninfected wounds well approximated (e.g., surgical incisions).
    • Healing by Second Intention: Wounds with extensive tissue loss (e.g., ulcers, large surface wounds). Requires more granulation tissue, fibrin, and inflammatory reaction.

    Complications of Wound Healing

    • Infection: A wound can become a portal of entry for microorganisms, delaying or stopping healing.
    • Deficient Scar Formation: Inadequate granulation tissue formation, insufficient ECM, or issues with contraction resulting in wound dehiscence (opening), hernias, or ulcerations.
    • Excessive Scar Formation: An excessive deposition of extracellular matrix (e.g., hypertrophic scars, keloids).

    Fracture Healing

    • Unlike skin wounds, fracture defects are repaired by bone-forming tissue, restoring bone to near normal.
    • Bone is composed of calcified osteoid tissue embedded in a mucoprotein matrix (osteomucin).

    Stages of Fracture Healing

    • Stage 1: Hematoma Formation: Immediate bleeding from torn vessels; blood can extend into surrounding muscles.
    • Stage 2: Inflammation: Tissue damage initiates an inflammatory response; increased blood flow, exudate and polymorphonuclear infiltration.
    • Stage 3: Demolition: Macrophages clear the clot, red blood cells, and inflammatory debris; removing detached bone fragments with necrosis.
    • Stage 4: Formation of granulation tissue: Capillary loops and mesenchymal cells grow into the defect from periosteum and endosteum of the cancellous bone, contributing to granulation tissue formation.
    • Stage 5: Woven bone and cartilage formation: Mesenchymal cells differentiate into osteoblasts forming woven bone or cartilage; “callus.”
    • Stage 6: Formation of lamellar bone: Dead calcified cartilage or woven bone is invaded by capillaries and osteoclasts; osteoblasts deposit osteoid that calcifies into bone in Haversian systems.
    • Stage 7: Remodelling: Continued osteoclastic removal and osteoblastic deposition of bone forms a bone structure similar to the original.

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    Pathology Lecture 4: Wound Healing PDF

    Description

    This quiz covers essential concepts of wound healing processes, including types of wounds, and cellular responses involved in tissue replacement. Understand the distinctions between closed and open wounds, as well as regeneration and repair mechanisms. Test your knowledge on the types of cells involved in wound healing.

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