Physiology The intrapleural pressure is negative both during inspiration and expiration because A Intrapulmonary pressure is always negative B Thoracic cage and lungs are elastic are elastic structure C Transpulmonary pressure determines the negativity D Surfactant prevents the lungs to collapse 💡 Explanation The intrapleural pressure is negative both during inspiration and expiration because ✓ Correct Answer: B. Thoracic cage and lungs are elastic are elastic structure