NEETZoologyBreathing and Exchange of Gases
In the physiological sequence of human respiration, which of the following events occurs immediately before the utilisation of O ₂ by the cells for catabolic reactions?
Options
- ATransport of respiratory gases by the blood
- BDiffusion of O ₂ and CO ₂ between blood and tissues
- CDiffusion of O ₂ and CO ₂ across the alveolar membrane
- DPulmonary ventilation by which atmospheric air is drawn in
Correct answer
B. Diffusion of O ₂ and CO ₂ between blood and tissues
Step-by-step solution
The physiological process of respiration in humans occurs in five sequential steps: 1. Pulmonary ventilation (breathing). 2. Diffusion of gases ( O ₂ and CO ₂ ) across the alveolar membrane. 3. Transport of gases by the blood. 4. Diffusion of O ₂ and CO ₂ between blood and tissues. 5. Utilisation of O ₂ by the cells for catabolic reactions and resultant release of CO ₂ (cellular respiration). The event that immediately precedes the cellular utilisation of O ₂ (step 5) is the diffusion of O ₂ and CO ₂ between the bl