23-7 Pulmonary Ventilation Alveolar Gas Content Alveoli contain less O2, more CO2 than atmospheric air Because air mixes with exhaled air 23-7 Pulmonary Ventilation Relationships and VT, VE, VA Determined by respiratory rate and tidal volume For a given respiratory rate: Increasing tidal volume increases alveolar ventilation rate For a given tidal volume: Increasing respiratory rate increases alveolar ventilation 23-7 Pulmonary Ventilation Respiratory Performance and Volume Relationships Total lung volume is divided into a series of volumes and capacities useful in diagnosing problems Four Pulmonary Volumes Resting tidal volume (Vt) Expiratory reserve volume (ERV) Residual volume Inspiratory reserve volume (IRV) 23-7 Pulmonary Ventilation Resting Tidal Volume (Vt) In a normal respiratory cycle Expiratory Reserve Volume (ERV) After a normal exhalation Residual Volume After maximal exhalation Minimal volume (in a collapsed lung) Inspiratory Reserve Volume (IRV) a normal inspiration 23-7 Pulmonary Ventilation Four Calculated Respiratory Capacities Inspiratory capacity Tidal volume + inspiratory reserve volume Functional residual capacity (FRC) Expiratory reserve volume + residual volume Vital capacity Expiratory reserve volume + tidal volume + inspiratory reserve volume
23-7 Pulmonary Ventilation Alveolar Gas Content Alveoli contain less O2, more CO2 than atmospheric air Because air mixes with exhaled air 23-7 Pulmonary Ventilation Relationships VT, VE, and VA Determined by respiratory rate and tidal volume For a given respiratory rate: Increasing tidal volume increases alveolar ventilation rate For a given tidal volume: Increasing respiratory rate increases alveolar ventilation 23-7 Pulmonary Ventilation Respiratory Performance and Volume Relationships Total lung volume is divided into a series of volumes and capacities useful in diagnosing problems Four Pulmonary Volumes Resting tidal volume (Vt) Expiratory reserve volume (ERV) Residual volume Inspiratory reserve volume (IRV) 23-7 Pulmonary Ventilation Resting Tidal Volume (Vt) In a normal respiratory cycle Expiratory Reserve Volume (ERV) After a normal exhalation Residual Volume After maximal exhalation Minimal volume (in a collapsed lung) Inspiratory Reserve Volume (IRV) a normal inspiration 23-7 Pulmonary Ventilation Four Calculated Respiratory Capacities Inspiratory capacity Tidal volume + inspiratory reserve volume Functional residual capacity (FRC) Expiratory reserve volume + residual volume Vital capacity Expiratory reserve volume + tidal volume + inspiratory reserve volume
ch_23_lecture_note.docx