Lecture Notes: Anatomy and Physiology - The Respiratory System

Introduction

• Presented by Andre from Med School EU
• Focus on the anatomy and physiology of the human respiratory system

Anatomy of the Respiratory System

Upper Respiratory Tract

• Nasal Cavity: The entry point at the top
• Pharynx: Located at the back of the throat
• Larynx: Contains the vocal cords, responsible for sound

Divide between Upper and Lower Respiratory Tract

• Trachea: The starting point of the lower respiratory tract

Lower Respiratory Tract

• Primary Bronchi: Splits off from the trachea to the lungs
• Lungs: Include further divisions down to the alveoli
• Bronchial Tree Breakdown:
  • Trachea → Primary Bronchi → Terminal Bronchioles → Respiratory Bronchioles → Alveolar Duct → Alveoli
  • Gas exchange occurs in the alveoli and sometimes in the alveolar duct

Diaphragm and Intercostal Muscles

• Diaphragm: Contraction stimulates breathing
• Intercostal Muscles: Located between ribs, aid lung inflation and deflation

Pleura

• Pleural Cavity: Space between the parietal (outer) and visceral (inner) pleura

Gas Exchange

• Principle of Diffusion: Moves from high to low partial pressure
• Oxygen: Higher partial pressure in alveoli, moves to capillaries
• Carbon Dioxide: Higher partial pressure in capillaries, moves to alveoli
• Exchange Reversal in Body Cells: Cells have high CO2 and low oxygen

Lung Lobes

• Right Lung: Three lobes
• Left Lung: Two lobes

Respiratory System Structures

• Trachea and Bronchi: Contain cartilage and goblet cells producing mucus
• Goblet Cells and Cilia: Protect against respiratory infections by trapping pathogens
• Smooth Muscle: Present in trachea, bronchus, terminal bronchioles

Gas Transport in Blood

• Oxygen: Carried by hemoglobin
• Carbon Dioxide: Transported predominantly as hydrogen carbonate (85%)
• Carbon Amino Hemoglobin: Accounts for 10% of CO2 transport

Physiology of Respiration

Inspiration (Inhaling)

• Muscle Contraction: Diaphragm and intercostal muscles increase lung volume
• Pressure Dynamics: Increase in volume decreases pressure; air flows in due to pressure gradient

Expiration (Exhaling)

• Muscle Relaxation: Elastic recoil of rib cartilage decreases lung volume
• Airflow: Occurs when lung pressure exceeds atmospheric pressure

Lung Volumes and Capacities

• Tidal Volume: Normal breath volume
• Total Lung Capacity: Maximum air lungs can hold
• Residual Volume: Air remaining in lungs after forced exhalation
• Functional Residual Capacity: Expiratory reserve volume + residual volume
• Inspiratory Reserve Volume: Additional air inhaled after normal inspiration
• Vital Capacity: Total of inspiratory reserve, tidal, and expiratory reserve volumes

Conclusion

• Next lecture to cover diseases in the circulatory and respiratory systems