Human Anatomy and Physiology: Lecture on Respiratory System - Conducting Zone

Introduction

• Lecture Series: Respiratory System
• Episode: 2
• Focus: Structures in the Conducting Zone
• Structures that bring air to the lungs but do not directly participate in gas exchange.

Respiratory System Overview

• Function: Key role in cellular respiration
  • Removes waste products like CO2
  • Maintains acid-base balance
• Zones:
  • Conducting Zone (Focus of this lecture)
  • Respiratory Zone (To be covered in subsequent lectures)

Conducting Zone Structures

• Nose and Nasal Cavity: Filters and warms incoming air.
• Pharynx (Throat):
  • Muscular tube for air and food passage.
• Larynx (Voice Box): Contains vocal cords, involved in sound production.
• Trachea: Reinforced with cartilaginous rings to keep airway open.
• Bronchi:
  • Right and left main bronchi bifurcate from the trachea to the lungs.
• Bronchioles: Smaller branches subdividing from bronchi.

Additional Structure

• Diaphragm: Large dome-shaped muscle essential for breathing.

Pharynx Divisions

• Nasopharynx:
  • Located within nasal cavity, serves only as an airway.
  • Contains tonsils.
• Oropharynx:
  • Passageway for air and food.
  • Bordered by nasopharynx (superiorly) and oral cavity (anteriorly).
• Laryngopharynx:
  • Inferior to oropharynx, posterior to larynx.
  • Connects pharynx to esophagus, involved in both respiration and digestion.

Epithelial Types in Pharynx

• Nasopharynx: Pseudostratified ciliated columnar epithelium
  • Contains cilia to propel mucus, remove debris and bacteria.
• Oropharynx and Laryngopharynx: Stratified squamous epithelium
  • Protects against abrasion from food passage.

Larynx

• Extends from laryngopharynx to trachea.
• Function: Regulates air volume entering lungs, involved in vocalization and swallowing.

Trachea

• Also known as windpipe, extends from larynx to lungs.
• Structure:
  • Contains hyaline cartilage for airway patency.
  • C-shaped cartilaginous rings allow esophageal expansion.
• Function: Maintains open airway from larynx to bronchi.

Bronchi and Bronchioles

• Main Bronchi:
  • Right and left primary bronchi divide into secondary and tertiary bronchi.
• Bronchioles: Smaller branches that continue to subdivide.

Conclusion

• The conducting zone structures are vital for directing air to the lungs but do not partake in gas exchange.
• Next episode will focus on the Respiratory Zone.