Respiratory Physiology

Flow rate

how quickly volume changes over time

Spirometer

measures the volume of air inhaled and exhaled (not including residual volume)

Respiratory Volumes

various volumes of air moved by or associated with the lungs at a given point in the respiratory cycle

Respiratory Capacities

combinations of two or more respiratory volumes

Tidal Volume

the amount of air inhaled or exhaled during one normal breath (a respiratory cycle)

Inspiratory Reserve Volume

the amount of air you can maximally inhale forcefully beyond a normal quiet/resting tidal inspiration (adult 2475 cc)

Expiratory Reserve Volume

the amount of air that can be forcefully exhaled following a passive exhalation (adult 1000 cc)

Vital Capacity

maximum amount of air that can be moved between maximal expiration and maximal inspiration

Functional Residual Capacity

volume of air remaining in the lungs after a passive exhalation

Total Lung Capacity

maximum amount of air the lungs contain after a maximal inspiration

Inspiratory Capacity

maximum amount of air that can be inhaled after a normal quiet expiration

Manometer

measures cm or inches of H2O elevated

Atmospheric Pressure

pressure exerted by the surrounding atmosphere (approx. 760 mm Hg)

Intraoral (mouth) Pressure

pressure measured within the oral cavity (same as subglottal if vocal folds are open)

Subglottal Pressure

pressure below the vocal folds

Pulmonic (alveolar) Pressure

pressure within the lungs and specifically in alveoli

Intrapleural (pleural-surface) Pressure

pressure between the visceral and parietal pleural membranes (remains constantly negative & becomes more negative during inspiration)