Q.6:- Explain the process of inspiration under normal conditions.
Inspiration is initiated by the contraction of diaphragm. The contraction of diaphragm increases the volume of thoracic chamber in the antero-posterior axis. The external inter-costal muscles contract to lift up the ribs and the sternum. This causes an increase in the volume of the thoracic chamber in the dorso-ventral axis. The overall increase in the thoracic volume results in a similar increase in pulmonary volume. The increase in pulmonary volume decreases the intra-pulmonary pressure to less than the atmospheric pressure. This pressure gradient forces the air from outside to move into the lungs and inspiration takes place.