What happens to lung pressure during inspiration?

During inspiration, lung pressure decreases as a result of the diaphragm contracting and the intercostal muscles expanding the thoracic cavity. This expansion creates a larger volume within the lungs, and according to Boyle's Law, when the volume of a container increases, the pressure within that container decreases. As the lung pressure falls below atmospheric pressure, air flows into the lungs from the external environment, leading to the inhalation process. This mechanics of pressure change is fundamental to the respiratory cycle, facilitating the movement of air into the lungs.