Explain the process of inspiration under normal conditions.

(N/A) Inspiration or inhalation is the process by which atmospheric air is drawn into the lungs.
It is initiated by the contraction of the diaphragm,which increases the volume of the thoracic chamber in the anteroposterior axis.
The contraction of external intercostal muscles lifts up the ribs and the sternum,causing an increase in the volume of the thoracic chamber in the dorsoventral axis.
The overall increase in thoracic volume leads to a corresponding increase in pulmonary volume.
An increase in pulmonary volume decreases the intra-pulmonary pressure to less than the atmospheric pressure,which forces the air from outside to move into the lungs,i.e.,inspiration.