Lecture Notes: The Respiratory System

Introduction

• The respiratory system is crucial for providing oxygen to every cell in the body and removing carbon dioxide.
• Oxygen is vital for cellular respiration, generating energy for the body.
• The respiratory system works in tandem with the circulatory system to transport oxygen.

Major Functions

• Supply oxygen to the body and remove carbon dioxide.
• Involves pulmonary ventilation (breathing) and external respiration (gas exchange between lungs and blood).

Components of the Respiratory System

• Nose and Nasal Cavity
  • Air enters through nostrils.
  • Nasal cavity separated from oral cavity by hard and soft palate.
  • Filters air, heats, and moistens it.
  • Surrounded by paranasal sinuses producing mucus.
• Pharynx (Throat)
  • Connects nasal cavity with the mouth.
  • Has three regions: nasopharynx, oropharynx, and laryngopharynx.
• Larynx (Voice Box)
  • Provides an airway and is the site of voice production.
  • Includes the epiglottis, vocal folds, and vestibular folds.
• Trachea (Windpipe)
  • Divides into primary bronchi leading to lungs.

Bronchi and Bronchioles

• Primary bronchi subdivide into secondary and tertiary bronchi.
• Further branches into bronchioles; smallest are less than a millimeter in diameter.
• Structural changes include thinner epithelium and more smooth muscle.

The Respiratory Zone

• Begins at the terminal bronchioles leading to respiratory bronchioles.
• Contains alveoli – sites for gas exchange.
• Alveoli have thin walls allowing for effective gas diffusion.

Lungs Structure

• Cone-shaped organs occupying the thoracic cavity.
• Surrounded by visceral and parietal pleura.
• Divided into lobes by fissures (3 lobes in right lung, 2 in left lung).
• Major Structures:
  • Hilum: where blood vessels and nerves enter and exit.
  • Cardiac notch: accommodates the heart.
• Lung tissue called stroma made of elastic connective tissue.

Pressure and Breathing

• Intrapulmonary Pressure: Pressure within alveoli.
• Intrapleural Pressure: Negative pressure maintaining lung openness.
• Breathing involves inspiratory muscles (diaphragm and intercostal muscles).

Conclusion

• The respiratory system works with circulatory system to effectively distribute oxygen and remove carbon dioxide.
• Understanding of the respiratory system complements knowledge of the circulatory system.