Arrange the following events of normal inspiration in the correct sequential order. A. Increase in pulmonary volume. B. Air moves into the lungs from the atmosphere. C. Contraction of diaphragm and external intercostal muscles. D. Decrease in intra-pulmonary pressure. E. Increase in the volume of the thoracic chamber. Choose the correct answer from the options given below :

Step-by-step solution

Inspiration is initiated by the contraction of the diaphragm and external intercostal muscles (C). This contraction increases the volume of the thoracic chamber in the antero-posterior and dorso-ventral axes (E). The overall increase in the thoracic volume causes a similar increase in pulmonary volume (A). An increase in pulmonary volume decreases the intra-pulmonary pressure to less than the atmospheric pressure (D). This negative pressure gradient forces the air from outside to move into the lungs from the atmosp