Lecture on the Respiratory System (AIT's Version 7)

Overview

• Focus: Human anatomy and physiology exam content on the respiratory system.

Parts of the Respiratory System

• Nasal Cavity

  • Function: Warms, humidifies, and filters air.
  • Structures: Nasal hairs and microscopic cilia.

• Pharynx

  • Crossroad for food and air pathways.

• Larynx (Voice Box)

  • Air travels down before reaching the trachea.

• Trachea

  • Cylindrical tube supported by cartilage rings.
  • Extends downward, splits into primary bronchi.

• Lungs

  • Two lungs; right lung has three lobes, left lung has two lobes.
  • Left lung has a cardiac notch for the heart.

• Bronchial Tree

  • Primary bronchi → Secondary bronchi → Tertiary bronchi → Bronchioles → Terminal bronchioles → Respiratory bronchioles → Alveolar ducts → Alveolar sacs.

Zones of the Respiratory System

• Conducting Zone

  • Includes trachea, bronchi, and terminal bronchioles.
  • Functions: Pass air to the respiratory zone, warm, humidify, and filter air.
  • Known as anatomical dead space (no gas exchange).

• Respiratory Zone

  • Includes respiratory bronchioles, alveolar ducts, and alveoli.
  • Functions: Gas exchange of oxygen and carbon dioxide.
  • Alveoli: Sites for blood oxygen intake and CO2 removal.

Gas Exchange and Circulatory System Connection

• Red Blood Cells

  • Collect oxygen from alveoli; dispose of CO2 as waste.

• Collaboration with Other Systems

  • Skeletal system (ribs protect lungs).
  • Muscular system (intercostal muscles, diaphragm, abdominal muscles aid in breathing).

Breathing Mechanics

• Inspiration (Inhalation)

  • Active process involving diaphragm and external intercostal muscles.
  • Diaphragm contracts, expanding thoracic cavity, causing negative pressure.

• Expiration (Exhalation)

  • Generally passive during rest, involving relaxation of breathing muscles.
  • Diaphragm and intercostal muscles relax, decreasing thoracic volume.
  • Forced expiration is active, e.g., during exercise or coughing.

Perfusion and Ventilation

• Ventilation

  • Movement of air in and out of lungs.
  • Ensures oxygen-rich air reaches alveoli.

• Perfusion

  • Blood flow to alveolar capillaries.
  • Balances with ventilation for optimal gas exchange.

Imbalances in Breathing

• Hypoventilation

  • Inadequate ventilation to meet body's needs.
  • Results: Increased CO2 (hypercapnia), decreased O2 (hypoxia).

• Hyperventilation

  • Excessive breathing rate/depth.
  • Results: Decreased CO2 (hypocapnia), increased O2 (hyperoxia).
  • Can cause respiratory alkalosis.

Conclusion

• Understanding of the respiratory system's structure and function is essential for AIT's exams.
• Additional resources are available for further learning and exam preparation.