The human respiratory system consists of a conducting part and an exchange (respiratory) part. Which of the following major steps of respiration corresponds strictly to the primary physiological function of the exchange part?

Step-by-step solution

According to NCERT, the respiratory system is divided into a conducting part and an exchange part. The exchange part (alveoli and their ducts) is the site of actual diffusion of O ₂ and CO ₂ between blood and atmospheric air. Therefore, the step 'Diffusion of gases ( O ₂ and CO ₂ ) across alveolar membrane' strictly represents the function of the exchange part. Pulmonary ventilation involves both parts to move air in and out. Transport of gases is a function of the cardiovascular system, and diffusion between blood