BIO 2091
McGilliard
 

LUNG VOLUMES:  DEFINITIONS


Spirometer  =  Instrument used to measure lung volumes.

Peak flow meter  =  Instrument used to measure air flow through the respiratory system.

Tidal volume  =  Volume of air entering or leaving the lungs in a single breath.
     Normal TV  =  500 ml.

Respiratory rate  =  Number of breaths per minute.  Normal RR  =  12 - 20 breaths/min.

Minute ventilation  =  Total volume of air breathed per minute.  MV  =  TV x RR.

Dead space  =  Volume of air in each breath which does not reach the alveoli.  This is
     approximately the volume of the conducting system.  Normal dead space  =  150 ml.

Alveolar ventilation  =  Volume of air which reaches the alveoli per minute.

Vital capacity  =  Maximum volume that can be exhaled after a maximal inspiration.
     This is measured using a spirometer.

Residual volume  =  Volume of air which is left in the lungs after a maximal expiration.
     Approximately 25% of vital capacity.

Total lung capacity  =  Volume of the lungs when completely inflated.
     TLC  =  vital capacity + residual volume.
 


 

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Updated 4/01/02