Final answer:
Static compliance refers to a change in lung volume in response to a transpulmonary pressure change without gas flow. This can happen because of the elastic properties of lung tissue and thoracic structures, and is governed by Boyle's Law, which states that, at constant temperature, the volume and pressure of a gas are inversely related.
Step-by-step explanation:
Static compliance involves the change in lung volume that occurs in response to a change in transpulmonary pressure when there is no gas flow, meaning during the time between inhalation and exhalation when airflow is zero. Despite there being no gas flow at this moment, the lungs can still experience a change in volume due to the elasticity of the lung tissue and the surrounding thoracic structures. When the muscles of respiration alter the size of the thoracic cavity, the pressure around the lungs changes, and due to the nature of the pulmonary system's compliance, the volume of the lungs can increase or decrease even without active airflow.
According to Boyle's Law, at constant temperature, the volume of a fixed amount of gas is inversely proportional to its pressure. This principle is what underlies lung function during breathing: as the volume of the thoracic cavity increases during inhalation, it causes a drop in intra-alveolar pressure, allowing air to flow into the lungs. Conversely, during exhalation, the volume of the thoracic cavity decreases, causing intra-alveolar pressure to rise and air to flow out of the lungs.