biology·NCERT Class 11·Breathing & Exchange of Gases
Alveolus Gas Exchange
Medium+70 XP
Every breath takes O₂ from 14,000 alveoli to your blood. The secret: oxygen diffuses DOWN its partial pressure gradient — from high in alveolar air to low in blood.
›Haemoglobin carries ~97% O₂ as oxyhaemoglobin; ~3% dissolved in plasma.
›CO₂ transport: 70% as bicarbonate (HCO₃⁻ via carbonic anhydrase); 23% as carbaminohaemoglobin; 7% dissolved.