Pulmonary ventilation is driven by a pressure gradient: inspiratory muscle action generates a negative intrapleural pressure, which is transmitted to the alveoli to produce a subatmospheric alveolar pressure and draw air into the lungs. The effectiveness of that ventilation is quantified by distinguishing minute ventilation from alveolar ventilation, the latter correcting for anatomical dead space that participates in no gas exchange, while the effort required is governed by airway resistance — dominated by airway radius — together with lung compliance and alveolar surface tension, which together define the work of breathing. This material belongs to respiratory physiology within human physiology, and it supplies the mechanical framework against which restrictive and obstructive lung disorders are classified by how each alters compliance, resistance, and the pressure and rate strategy a patient must adopt to ventilate.
Pulmonary ventilation is driven by a pressure gradient: inspiratory muscle action generates a negative intrapleural pressure, which is transmitted to the alveoli to produce a subatmospheric alveolar …