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Key Terms

  • Nonspecific defense: General mechanisms defending the body.
  • Cell-mediated immunity: Immune response involving T-cells.
  • Inflammation: Protective response to injury or infection.
  • Bradykinin: A peptide that causes blood vessels to dilate and increases permeability.
  • Exudate: Fluid that leaks out of blood vessels into surrounding tissues during inflammation.
  • Resolution: Return to normal tissue after inflammation.
  • Regeneration: Replacement of damaged tissue with functional cells.
  • Replacement: Replacement of functional tissue with non-functional scar tissue.
  • Healing by first intention: Minimal tissue damage leading to small scars.
  • Healing by second intention: More severe damage and larger scars.
  • Deep partial-thickness burn: Affects deeper skin layers.
  • Full-thickness burn: Extensively damages all skin layers and underlying tissues.

Review of Body Defenses

  • First Line of Defense:

    • Nonspecific mechanisms, including:
    • Mechanical/Chemical Barriers: Unbroken skin and mucous membranes.
    • Secretions: Tears and gastric juices.

  • Second Line of Defense:

    • Also nonspecific and includes:
    • Phagocytosis: Engulfing of pathogens.
    • Inflammation: Localized response to injury.
    • Interferons: Proteins that interfere with viral replication.

  • Third Line of Defense:

    • Specific mechanisms:
    • Antibodies: Produced against specific antigens.
    • Cell-Mediated Immunity: Involves T-cells and other immune cells.

Physiology of Inflammation

  • Definition: Inflammation is a protective response, is not synonymous with infection but can be caused by it.
  • Etiology: Causes include physical injury, chemical damage, infections, allergies, temperature extremes, ischemia, and foreign bodies.
  • Signs and Symptoms: Serve as indicators of underlying issues.

Steps of Inflammation

  1. Injury: Triggers bradykinin release from damaged cells.
  2. Pain: Bradykinin stimulates pain receptors, leading to histamine release.
  3. Vasodilation: Caused by bradykinin and histamine, increasing blood flow.
  4. Phagocytosis: Neutrophils and macrophages engulf pathogens.

Acute Inflammation

  • Local Effects:
    • Redness, warmth, swelling (edema), pain, potential loss of function.
  • Systemic Effects:
    • Mild fever (pyrexia), headache, malaise, fatigue, anorexia.
  • Complications:
    1. Infection: Inflammatory exudate fosters microbial growth.
    2. Skeletal Muscle Spasm: Pain-induced contractions.

Exudate

  • Types of Exudate:
    A. Serous: Watery fluid with proteins and white blood cells.
    B. Fibrinous: Thick, sticky with high fibrin content.
    C. Purulent: Thick, yellow-green with leukocytes and debris.

Chronic Inflammation

  • Occurs following acute inflammation; fewer exudate but more immune cells (lymphocytes, macrophages, fibroblasts).
  • Complications:
    1. Deep Ulceration: Tissue necrosis due to persistent inflammation.
    2. Granulomas: Form around foreign materials.
    3. Fibrosis: Excess scar tissue formation.

Healing Types

  1. Resolution: Minimal damage (e.g., mild sunburn).
  2. Regeneration: Damaged tissue replaced with similar cells (e.g., epithelial cells).
  3. Replacement: Functional tissue replaced with non-functional scar tissue (e.g., in nervous system).

Healing Processes

  • Healing by First Intention: Clean wounds, minimal scarring.
  • Healing by Second Intention: Severe injury, larger scars.

Scar Formation Complications

  1. Loss of Function: Due to loss of normal cells.
  2. Contractures and Obstructions: Restricted movement due to joint deformity.
  3. Adhesions: Scar tissue connecting separated body parts.
  4. Hypertrophic Scars: Overgrowth of scar tissue.
  5. Ulceration: Impaired blood supply leading to further breakdown.

Burns

  • Causes: Heat, chemicals, electricity, radiation, friction.
  • Classification:
    A. Superficial Partial-Thickness (First-Degree): Affects epidermis, heals without scarring.
    B. Deep Partial-Thickness (Second-Degree): Involves epidermis and dermis, painful and blistered.
    C. Full-Thickness (Third & Fourth-Degree): Destroys all skin layers, requires grafting.

Healing of Burns

  • Long process requiring clean wound management to prevent infections.
  • Physiotherapy and surgery may be necessary to manage scar tissue.