![]() ![]() The lungs and chest wall have elastic properties. The discussion of pulmonary physiology begins with an introduction to a few concepts about the mechanical properties of the respiratory system, which have important implications for assessment of pulmonary function and its derangement in disease states. Mechanical Aspects of the Lungs and Chest Wall On completion of gas exchange and travel through the pulmonary capillary bed, the oxygenated blood flows through pulmonary venules and veins and arrives at the left side of the heart for pumping to the systemic circulation and distribution to the tissues.įurther details about the anatomy of airways, alveoli, and the pulmonary vasculature, particularly with regard to structure-function relationships and cellular anatomy, are given in Chapters 4, 8, and 12. ![]() The capillaries generally allow red blood cells to flow through in single file only so that gas exchange between each cell and alveolar gas is facilitated. After blood arrives at the lungs via the pulmonary artery, it courses through a widely branching system of smaller pulmonary arteries and arterioles to the major locale for gas exchange, the pulmonary capillary network. The pulmonary capillary network and the blood within provide the other crucial requirement for gas exchange: a transportation system for O 2 and CO 2 to and from other body tissues and organs. This vast surface area of gas in contact with alveolar walls is a highly efficient mechanism for O 2 and CO 2 transfer between alveolar spaces and pulmonary capillary blood. ![]() It is estimated that the adult human lung has on the order of 300 million alveoli, with a total surface area approximately the size of a tennis court. The surface area for gas exchange provided by the alveoli is enormous. The acinus includes structures distal to a terminal bronchiole: respiratory bronchioles, alveolar ducts, and alveoli (alveolar sacs). ![]()
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