Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Inspiration can occur if the intra-pulmonary pressure is less than the atmospheric pressure. Reason (R): Contraction of diaphragm and external intercostal muscles decreases the overall thoracic volume, creating a negative pressure in the lungs. In the light of the above statements, choose the most

Step-by-step solution

Assertion (A) is a correct statement. Inspiration occurs when the pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure, establishing a negative pressure gradient. Reason (R) is an incorrect statement. The contraction of the diaphragm and external intercostal muscles increases, not decreases, the overall thoracic volume. This increase in thoracic volume leads to an increase in pulmonary volume, which in turn decreases the intra-pulmonary pressure below atmospheric pressure, caus