title: [The physiology of intrathoracic pressure changes (author's transl)].
abstract: The pleural cavity, because of the thin film of fluid between the pleural layers, acts like a capillary space within which capillary forces operate. It is due to these forces that the lungs follow the respiratory movements of the thoracic cage and diaphragm and are kept expanded within the thorax. "Subatmospheric" pressure in the pleural cavity develops only if the capillary space is opened by injury to one of the pleural layers, thus allowing the elastic pull of the thoracic cage and lungs to act on the pleural cavity. The subatmospheric pressure registered by the exploratory needle is, in fact, non-existent in the normal chest. It owes its existence to the introduction of the needle which causes separation of the pleural layers and the introduction of a small quantity of air. The pulling and stretching forces exerted by the thorax and lungs on the air bubble then become measurable as subatmospheric pressure. The same forces operate during the respiratory movements and induce changes in volume and pressure in all air or fluid containing spaces. The result is a delicately regulated consonance of aire movement and blood distribution. Simplified graphs illustrate the interconnections.
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D002197:Capillary Action; D006801:Humans; D011312:Pressure; D013909:Thorax / Q000502:physiology*
vernacular_title: Der physiologische Druckablauf im Thorax.