This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mechanics of Respiration, Subject name: Physiology
In inspiration the intrapleural pressure become: (PGI Dec 2006) 
Select and explain. 
A. More -ve, B. More + ve, C. Same as expiratory level, D. Initially positive then negative
A: More -ve
Answer: A: More -ve 
Explanation: Ans: A (More negative) The intrapleural pressure at the base of lungs, which is normally about -2.5 mm Hg+ (relative to atmospheric) at the start ofinspiration, decreases to about-6 mm of HgQ"- Ganong 22nd / 651Strong inspiratory efforts can reduce intrapleural pressure to values as low as -30 mm Hg -Ganong22nd/651Fig (Ganong 23rd/592): Pressure in alveoli & the pleural space relative to atmospheric pressure during inspiration & expiration