Question

Complete the following statement using the choices below.

Air moves out of the lungs when the pressure inside the lungs is

• A. Less than the pressure in the atmosphere
• B. Greater than the pressure in the atmosphere
• C. Equal to the pressure in the atmosphere
• D. Greater than the intra-alveolar pressure

Answer 1

The correct option is B

Greater than the pressure in the atmosphere

The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere. Inspiration can occur if the pressure within the lungs (intrapulmonary pressure) is less than the atmospheric pressure, i.e., there is a negative pressure in the lungs with respect to atmospheric pressure. Similarly, expiration takes place when the intrapulmonary pressure is higher than the atmospheric pressure.