On what breathing method does the human respiratory system rely? Describe the process of inhalation.
The human respiratory system relies on a breathing method called negative-pressure breathing. Inhalation is brought about by the increase in the volume of the thoracic cavity. Such an increase causes the air pressure in the cavity to drop below atmospheric pressure and, thus, air to be drawn into the lungs. The contraction of the rib cage's muscles, which causes the cage to move up and out, and the contraction of the diaphragm, the muscular partition between the thoracic and abdominal cavities, downward into the abdominal cavity, effects the increased volume of the thoracic cavity.
