Respiratory System Overview

Introduction to Breathing

• Ventilation: The process of breathing.
• Essential for air exchange in the lungs.

Anatomy of the Airways

• Trachea: Main airway to the lungs.
  • Maintained open by C-shaped rings of cartilage.
  • Vital for preventing asphyxiation (patency).

Larynx and Associated Structures

• Larynx: Located above the trachea.
  • Contains vocal cords.
  • Made of thyroid cartilage (known as the Adam's apple).
• Cricoid Cartilage: Complete ring of cartilage below the larynx.
• Cricothyroid Ligament: Area between thyroid and cricoid cartilage; site for emergency airway procedures (cricothyroidotomy).

Oesophagus

• Positioned immediately posterior to the trachea.
  • Has a thick muscular wall for food passage.
  • Design of trachea allows food distortion without obstruction.

Bronchial Tree Structure

• Main Bronchi: Trachea divides into left and right main bronchi.
  • Right Main Bronchus: Straight, more vertical.
  • Left Main Bronchus: Angled, leads to left lung.
• Lobar Bronchi:
  • Left lung: 2 lobes (upper and lower).
  • Right lung: 3 lobes.
• Segmental Bronchi: Further dividing into smaller branches.
• Bronchioles: Smallest air passages leading to alveoli.

Fractal Pattern of Bronchial Tree

• Fractal Design: Each division mimics the previous one, allowing for equal air distribution.
• Bronchitis: Inflammation of the bronchi, common in smoky environments.

Lung Structure

• Shape of Lungs: Extend downwards and upwards.
• Lobar Pneumonia: Infection limited to a lobe, common in young adults.

Thoracic Cavity and Muscles of Breathing

• Ribs: 12 pairs surrounding the lungs; contain intercostal muscles.
  • External Intercostal Muscles: Outward muscles between ribs.
  • Internal Intercostal Muscles: Inward muscles.
• Diaphragm: Large muscle at base of thoracic cavity.
  • Supplies 75% of respiratory effort in resting breathing.
  • Innervated by phrenic nerves.

Conclusion

• Next section will cover how these structures move for inspiration and expiration.