In physiology,<unk>  refers to the<unk>  within the pleural cavity. Normally, the<unk>  within the pleural cavity is slightly less than the atmospheric<unk> , which is known as negative<unk> . When the pleural cavity is damaged or ruptured and the<unk>  becomes greater than the atmospheric<unk> , pneumothorax may ensue.<unk>  is different from intrathoracic<unk> . The thoracic cavity is the space that includes the pleura, lungs, and heart, while the pleural space is only the space between the parietal pleura and visceral pleura surrounding lungs.<unk>  depends on the ventilation phase, atmospheric<unk> , and the volume of the<unk>  cavity. At rest, there is a negative<unk> . This provides a transpulmonary<unk>  A person breathing at rest inhales and exhales approximately half a liter of air during each respiratory cycle, which is called tidal volume. The respiratory rate is directly affected by the concentration of carbon dioxide in the blood. Lungs do not collapse after forceful respiration because of the residual volume.
Intrapleural pressure
Alveolar pressure
Alveolar–arterial gradient
Cricoid pressure
Transpulmonary pressure
Lung compliance
Right atrial pressure
Residual volume