Gas Exchange in the Alveoli

Structure of Alveoli

• Location: At the end of the bronchioles in the lungs.
• Shape: Often described as cauliflower-shaped, but essentially tiny air sacs.
• Diagram Representation: Helps visualize the process of gas exchange.

Gas Exchange Process

• Oxygen and Carbon Dioxide Movement:
  • Constantly supplied and removed through breathing.
  • Oxygen diffuses across the alveolus' lining (one cell thick) and into blood capillaries.
  • Oxygen binds with hemoglobin to form oxyhemoglobin.
  • Carbon dioxide diffuses in the opposite direction to be expelled from the body.
• Concentration Gradient: Maintained by continuous breathing and blood flow, facilitating ongoing gas exchange.

Features of Gas Exchange Surface

• Large Surface Area:
  • Provided by the shape of alveoli and their large numbers.
• Thin Structure:
  • Lining is only one cell thick, facilitating short diffusion pathways.
• Moist Lining:
  • Allows gases to dissolve, facilitating diffusion.
• Good Blood Supply:
  • Dense capillary network surrounds each alveolus, optimizing gas exchange.
• Ventilation:
  • Efficient air supply maintained through breathing.

Microscopic View of Lung Tissue

• Capillary Network:
  • Appears as a crisscross mesh.
  • Red splotches correspond to individual red blood cells.

Exam Tips

• Key Points for Efficient Gas Exchange:
  • Large surface area due to numerous alveoli.
  • Surface is one cell thick for short diffusion pathway.
  • Dense capillary network provides excellent blood supply.
• Marks: Knowledge of these features can secure marks in exam questions about efficient gas exchange.