Inspiration occurs when intrapulmonary pressure falls below atmospheric pressure, and air moves into the lungs.

当肺内压降到大气压以下，并且空气进入肺部时，就会发生吸气。

That decreased lung volume increases the intrapulmonary pressure, and that pushes air out of the lungs.

肺容积减少会增加肺内压，并将空气排出肺。

As stated previously, inspiration occurs as a result of increased lung volume and then decreased intrapulmonary pressure.

如前所述，吸气是由于肺容积增加，然后肺内压力降低。

Intrapulmonary pressure falls below atmospheric pressure when the diaphragm contracts and increases the thoracic volume.

当隔膜收缩并增加胸腔容积时，肺内压降至大气压以下。

After the diaphragm contracts, it relaxes, thus decreasing thoracic volume and increasing intrapulmonary pressure.

膈肌收缩后，松弛，从而减少胸腔容积并增加肺内压力。

Transpulmonary pressure is the difference between the intrapleural pressure (outside of the lungs) and the intrapulmonary pressure (that's inside the lungs).

肺间压（Transpulmonary pressure）指胸膜内压（肺外）和肺内压（肺内）之间的差值。

The intrapleural pressure is the pressure within the pleural cavity and it is always less than intrapulmonary pressure, which is the pressure inside the lung.

胸膜腔内压指胸膜腔内的压力，肺内压指肺内的压力，胸膜腔内压始终小于肺内压。

The lung pressure (or more specifically, intrapulmonary pressure), becomes less than atmospheric pressure, and that creates a pressure gradient, or a difference between the two pressures.

肺压力（或者更具体地说，肺内压力）变得比大气压力小，这就产生了压力梯度，或者两种压力之间的差异。