Chapter 17: Breathing and Exchange of Gases – Part 2
✅ Chapter 17: Breathing and Exchange of Gases – Part 2 🔍 Exchange of Gases and Transport of Respiratory Gases 📚 Gas Exchange at the Alveoli: The actual exchange of oxygen (O₂) and carbon dioxide (CO₂) between the lungs and blood occurs at the alveolar surface . Alveoli are tiny, balloon-like structures that provide: Large surface area Thin walls Rich capillary network ✅ Key point: Alveoli and capillaries together form the respiratory membrane , which is extremely thin (~0.5 micrometers). ⚙️ Mechanism of Gaseous Exchange: Passive Diffusion is the main mechanism based on differences in partial pressure . Gas Alveolar Air (mm Hg) Deoxygenated Blood (mm Hg) Oxygen (O₂) 104 40 Carbon dioxide (CO₂) 40 45 ✅ Direction of diffusion: O₂ diffuses from alveoli → blood (higher to lower partial pressure). CO₂ diffuses from blood → alveoli. Thus, gases move down their pressure gradients without requiring energy. 🌍 Partial Pressure: Par...