Lecture on Asthma

Normal Airway Structure

• Airway Anatomy
  • Asthma affects small airways (not trachea or throat)
  • Important component: Smooth muscle layer
    • Controls diameter of airway lumen
    • Involuntary muscle, reacts to environment
  • Other components: connective tissue, cartilage (not significantly affected by asthma)
• Mucosal Layer
  • Coats the inside of the airway
  • Contains glands that secrete mucus
    • Lubricates and keeps lungs moist
    • Helps clear out foreign bodies and inflammation
• Lumen
  • The passage where air moves
  • Kept lubricated by mucus

Asthma and Its Effects

• During an Asthma Attack
  • Muscular layer spasms, thickens, constricts lumen
  • Mucosal layer swells due to inflammation
  • Glands over-secrete mucus, filling and obstructing lumen
  • Results in wheezing and popping sounds due to narrowed passage and mucus
• Triggers of Asthma
  • Environmental factors: pollution, smoke, food, dander
  • Allergic reaction triggered by allergens

Immune Response in Asthma

• Allergies and Antibodies
  • Allergens trigger immune response
  • IgE antibodies recognize and react to allergens
    • Increase in IgE response with repeated exposure
• Role of Mast Cells and Histamine
  • IgE attaches to mast cells releasing histamine
  • Histamine causes allergy symptoms: sneezing, watery eyes, hives
  • In asthma, leads to airway constriction and symptoms

Key Points of Asthma Pathophysiology

1. Muscle Layer
   • Thickens and constricts airway
2. Mucosal Layer
   • Swells, reducing airway size
3. Gland Activity
   • Overproduction of mucus further obstructs airway

Asthma is essentially an overactive immune response to a foreign body leading to airway constriction and respiratory symptoms.