Lecture on Gas Exchange System and Filtration

Purpose of Gas Exchange System

• Functions to filter dust and pathogens from inhaled air.
• Importance varies based on environment (e.g., cities have higher pollutants).
• Protection of lung tissue from damage by dust and pathogens is crucial.

Filtration Mechanisms

Goblet Cells

• Located in the trachea and bronchi.
• Release mucin/mucus to trap dust and pathogens.
• Mucin and mucus terms can be used interchangeably.

Mucin Production

• Begins with transcription: genes in the nucleus produce mRNA.
• mRNA moves to the rough ER for translation, forming polypeptide chains (protein synthesis).
• Polypeptide chains are modified in the Golgi apparatus by adding carbohydrates, forming glycoproteins.
• Glycoprotein mucin is packaged into vesicles, released by exocytosis.
• Mucin/mucus remains on epithelial surface, sticky to trap dust and pathogens.

Ciliated Epithelium

• Cilia move mucus upwards toward the throat.
• Mucus swallowed, allowing stomach acids and enzymes to digest trapped particles.
• Sneezing or coughing expels excess dust/pathogens.

Bronchiole Response During Exercise

• Bronchioles have ciliated epithelium and smooth muscle cells.
• Smooth muscle contraction/relaxation affects lumen size:
  • Standing: Muscles contract, lumen smaller.
  • Running: Muscles relax, lumen larger.
• Larger lumen during exercise increases air flow to alveoli, enhancing oxygen diffusion into blood.

Adaptations for Exercise

• Absence of cartilage allows lumen size changes.
• Increased oxygen diffusion during exercise supports aerobic respiration and ATP production.

Key Takeaways

• Filtration process is vital for lung protection and involves mucus production and cilia function.
• Bronchioles adapt during exercise to ensure oxygen supply meets increased demand.
• Understanding these mechanisms is crucial for respiratory health and effective gas exchange.