Final answer:
During inspiration, transpulmonary pressure becomes slightly higher as lung volume increases, resulting in a lower intra-alveolar pressure according to Boyle's law, thus facilitating airflow into the lungs due to the pressure gradient created with respect to the atmospheric pressure.
Step-by-step explanation:
Transpulmonary pressure is the difference in pressure between intrapleural and intra-alveolar pressures. During inspiration, transpulmonary pressure becomes slightly more as the thoracic cavity volume increases due to the action of the diaphragm and intercostal muscles. This increase in volume leads to a decrease in intra-alveolar pressure, according to Boyle's law, which describes the inverse relationship between volume and pressure. Therefore, during inspiration, as lung volume increases, the intra-alveolar pressure drops, creating a pressure gradient where the air flows into the lungs where the pressure is lower, equalizing the intra-alveolar pressure with the outside atmospheric pressure.
Furthermore, transpulmonary pressure is an indicator of lung expansion, where a higher pressure correlates with a larger lung volume. This pressure gradient is the driving force behind pulmonary ventilation, causing air to move from an area of higher pressure to an area of lower pressure, allowing for effective breathing and oxygen exchange.
In summary, the difference in pressures, namely the atmospheric pressure, intra-alveolar pressure, and intrapleural pressure, along with the physical characteristics of the lung such as elasticity and resistance, dictate the efficiency of the pulmonary ventilation process.