You do not suck air in. You make room for it. The diaphragm changes the size of your chest. That changes the pressure inside (Boyle's law), and air follows. Watch it breathe.
Inhalation
Breathing mechanicsvolume drives pressure
Thoracic volume
Lung pressure
📷 Reference image
A real labeled figure to compare with the interactive above.
Breathing Mechanics — OpenStax, CC BY 4.0 (via Wikimedia Commons)
