(BQ) Part 2 book “West’s respiratory physiology” has contents: Mechanics of breathing, control of ventilation, respiratory system under stress, tests of pulmonary function - How respiratory physiology is applied to measure lung function. | Mechanics of Breathing How the Lung is Supported and Moved 7 • Muscles of Respiration Inspiration Expiration • Elastic Properties of the Lung Pressure-Volume Curve Compliance Surface Tension • Cause of Regional Differences in Ventilation Airway Closure • Elastic Properties of the Chest Wall • Airway Resistance Airflow Through Tubes Measurement of Airway Resistance Pressures During the Breathing Cycle Chief Site of Airway Resistance Factors Determining Airway Resistance Dynamic Compression of Airways • Causes of Uneven Ventilation • Tissue Resistance • Work of Breathing Work Done on the Lung Total Work of Breathing 108 W e saw in Chapter 2 that gas gets to and from the alveoli by the process of ventilation. We now turn to the forces that move the lung and chest wall, and the resistances that they overcome. First, we consider the muscles of respiration, both inspiration and expiration. Then we look at the factors determining the elastic properties of the lung, including the tissue elements and the air-liquid surface tension. Next, we examine the mechanism of regional differences in ventilation and also the closure of small airways. Just as the lung is elastic, so is the chest wall, and we look at the interaction between the two. The physical principles of airway resistance are then considered, along with its measurement, chief site in the lung, and physiological factors that affect it. Dynamic compression of the airways during a forced expiration is analyzed. Finally, the work required to move the lung and chest wall is considered. MECHANICS OF BREATHING 109 Muscles of Respiration Inspiration The most important muscle of inspiration is the diaphragm. This consists of a thin, dome-shaped sheet of muscle that is inserted into the lower ribs. It is supplied by the phrenic nerves from cervical segments 3, 4, and 5. When it contracts, the abdominal contents are forced downward and forward, and the vertical dimension of the chest cavity is increased. In addition, .
