Final answer:
During inspiration, lung compliance is higher at the beginning when the lungs are more pliable and can expand easily, but it decreases as the lungs become more filled with air and less capable of further expansion.
Step-by-step explanation:
Compliance is defined as the change in volume (ΔV) per unit of pressure change (ΔP). During inspiration, the compliance of the lungs is usually higher at the initial stage because the lungs are more pliable and can expand more readily. However, as the lungs fill up with air, their compliance generally decreases because they become less capable of expanding without a large increase in pressure. This is due to the elastin and other structural components in the lung tissue stretching to accommodate the incoming air, leading to a decrease in compliance as the lung reaches fuller capacity.
Pulmonary diseases that make the lungs stiff and less pliable cause the compliance to decrease. Moreover, when there is increased resistance in the lung, usually due to obstruction in the airways, breathing becomes more difficult, reflecting a decrease in the ability of lungs to accommodate air flow.