What happens to the pressure inside the lungs while a person inhales?

1. Air flows from higher pressure toward lower pressure. 2. To draw air in, the lungs must be at a lower pressure than the outside air. 3. Muscles in the diaphragm and rib cage increase the volume of the lungs, which lowers the pressure inside them below atmospheric, a negative gauge pressure. 4. On exhaling the pressure rises above atmospheric instead, which is a positive gauge pressure, so the two must not be swapped. 5. A steady match with atmospheric pressure would mean no air moved at all. _Source: OpenStax College Physics (CC BY 4.0), Ch 11 "Fluid Statics", section 11.9 Pressures in the Body_