ABSTRACT
This chapter describes the lung mechanical properties and their function as a transfer organ for gases such as oxygen and carbon dioxide. From a functional point of view, the respiratory system can be divided into three components: the ventilatory pump, an air distribution network, and a blood and gases exchange zone. From a functional point of view, the circulatory system can also be divided into three components: the circulatory pump, a blood distribution network, and an exchange zone for gas transfer. The elastic properties of the lung depend of the fibroelastic tissue network constituting the lung parenchyma and, in turn, provides structural support to the alveolar walls. When the lung and the rib cage are coupled and no respiratory muscle is active, the lung is at functional residual capacity (FRC). Expiratory flow depends on three factors: elastic recoil of the lung, the critical closing pressure of airways, and the airway resistance upstream of the compressible segment.
