NEET2016ZoologyBreathing and Exchange of GasesActual
Lungs does not collapse between breaths and some amount of air will always remain in the lungs which can never be expelled because,
Options
- AThere is a negative pressure in the lungs
- BThere is a negative intrapleural pressure pulling at the lung walls
- CThere is a positive intrapleural pressure
- DPressure in the lungs is higher than the atmospheric pressure
Correct answer
B. There is a negative intrapleural pressure pulling at the lung walls
Step-by-step solution
The pressure within the pleural cavity is slightly less than that of atmospheric pressure and this is referred to as negative pressure. Hence, the lungs do not collapse between breaths and some air always remains in it. Even after the most forceful expiration, there will be sufficient volume of air in the lungs. This is called residual volume. It is about 1.2 litre in males and 1.1 litre in females.