Bio 449 Lecture 21 – Respiratory Physiology II Oct. 27, 2010 Mechanics of ventilation Pressure and pumps Thoracic cavity Intrapleural pressure Inspiration and expiration Alveolar gas composition Atmospheric gases Partial pressures Effects of ventilation pattern Anatomical dead space Alveolar gases Terms to Know Thoracic cavity Diaphragm Pleural membrane Intrapleural fluid Compliance Inhalation Exhalation External intercostals Internal intercostals Partial pressure Tidal volume Anatomical dead space Minute ventilation Alveolar ventilation Readings Lectures 21-22: Chapter 17 Lectures 23-24: Chapter 16, pages 547-558 Chapter 18

Mechanics of ventilation Pressure and pumps

Thoracic cavity

Pleural cavities Fig. 17-11 Diaphragm Right pleural cavity Left pleural cavity Fig. 17-11

Pleural cavities Right lung Pericardial cavity Right pleural cavity Pleural membranes Left pleural cavity Left Heart Fig. 17-2

Fig. 17-12 Intrapleural space Pleural membranes Diaphragm P = –3 mm Hg Ribs Fig. 17-12

Inspiration and expiration

The rib cage expands slightly. Pneumothorax P = Patm Lung collapses to unstretched size Knife Intrapleural space Pleural membranes If the sealed pleural cavity is opened to the atmosphere, air flows in. The rib cage expands slightly. Air Fig. 17-12

Alveolar gas composition Atmospheric gases

Partial pressures

Alveolar ventilation

Alveolar ventilation 2 3 4 1 150 150 mL 350 2700 mL 2200 mL Fig. 17-14

Alveolar gases