Human Respiratory System

Overview

• The human respiratory system is vital for life.
• We breathe 16,000 to 24,000 times per day, exchanging about 11,000 liters of air.
• Functions:
  • Delivering oxygen to tissues.
  • Removing carbon dioxide from the body.

Anatomy and Physiology

Division of the Respiratory Tract

• Upper Respiratory Tract:
  • Nasal cavity
  • Pharynx
  • Part of the larynx above the vocal cords.
• Lower Respiratory Tract:
  • Part of the larynx below the vocal cords
  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli

Nose and Nasal Cavity

• Structure:
  • Roof: Bones forming the base of the skull.
  • Floor: Palatine bones.
• Functions:
  • Filtration: Cilia trap dust and pollutants.
  • Humidification/Warming: Prevents dryness in respiratory membranes.

Oral Cavity

• Secondary opening for respiratory tract:
  • Pros: Wider opening for air intake (during exercise).
  • Cons: No filtration, humidification, or temperature regulation.

Pharynx

• Muscular tube connecting:
  • Nasal cavity and larynx.
  • Oral cavity and esophagus.
• Parts:
  • Nasopharynx: Behind nasal cavity.
  • Oropharynx: Behind oral cavity.
  • Laryngopharynx: Behind larynx.
• Epiglottis: Prevents food entry into trachea.

Larynx

• Known as the voice box / Adam's apple.
• Functions:
  • Connects pharynx to trachea.
  • Produces sound/speech.

Trachea

• Tube connecting larynx to bronchi.
• Structure: 20 C-shaped cartilages prevent collapse.
• Divides into primary bronchi:
  • Further divides into secondary and tertiary bronchioles.
  • Ends in alveoli.

Gas Exchange

Alveoli

• Sac-like structures where gas exchange occurs:
  • Conducting bronchioles: No gas exchange.
  • Respiratory bronchioles: Some gas exchange.
• Alveoli are surrounded by capillaries for efficient gas exchange.

Circulatory System Interaction

• Deoxygenated blood enters the lungs via pulmonary arteries:
  • Gas exchange converts it to oxygenated blood.
• Oxygenated blood is pumped back to the heart and distributed to the body.
• Approximately 250-300 million alveoli facilitate gas exchange for 5 liters of blood.

Gas Transport in Alveoli

• Close proximity between alveolar air and blood vessels:
  • Diffusion occurs due to concentration differences:
    • Carbon Dioxide: Higher in blood, lower in alveolar air (exchanges out).
    • Oxygen: Higher in alveolar air, lower in blood (exchanges in).
• Deoxygenated blood converts to oxygenated blood at capillaries.

Conclusion

• Brief overview of human respiratory system functions and structure.
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