Select the correct statement about breathing in man.
Inspiration can occur if the pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure, i.e., there is a negative pressure in the lungs with respect to atmospheric pressure. Inspiration is initiated due to the contraction of the diaphragm. Contraction of the diaphragm increases the volume of the thoracic chamber in vertical axis. Any change in the thoracic volume will be reflected in the lung volume.