Flow of air into and out of the lungs can be attributed to
A) a pressure gradient between the atmosphere and the alveoli
B) a pulsating contraction and relaxation movement of the trachea
C) the air turbulence created in the nasal conchae
D) the rigidity of the diaphragm that maintains the pressure in the thorax
E) a change in the volume of the intrapleural fluid

Question

Quizplus · Accepted Answer

The flow of air into and out of the lungs is due to a pressure gradient between the atmosphere and the alveoli. During inhalation, the diaphragm contracts and the intercostal muscles expand the ribcage, creating a larger volume in the thoracic cavity. This decrease in pressure allows air to rush into the lungs. During exhalation, the opposite occurs - the diaphragm relaxes and the ribcage contracts, decreasing the volume in the thoracic cavity and increasing the pressure, forcing air out of the lungs.

Flow of Air into and Out of the Lungs Can