QS Study

Lungs Volumes and Capacities with their Normal Value

The pulmonary volumes added together equal the maximum volume to which the lungs can be expanded. Lung volumes and lung capacities refer to the volume of air connected with dissimilar phases of the respiratory cycle. The regular total lung capacity of an adult human male is about 6 liters of air.

  1. Tidal volume (TV): It is the volume of air inspired or expired with each normal breath. It is the amount of air inspired by normal, relaxed breathing.

Normal value in adult – 500 ml.

  1. Inspiratory reserve volume (IRV): It is the maximum extra volume of air that can be inspired over and above the normal tidal volume.

Normal value in adult – 3000 ml.

  1. Expiratory reserve volume (ERV): It is the maximum extra volume of air that can be expired by forced expiration, after the end of a normal tidal expiration.

Normal value in adult – 1100 ml.

  1. Residual volume (RV): It is the volume of air remaining in the lungs after the most forceful expiration. It is the volume of air still remaining in the lungs after the expiratory reserve volume is exhaled.

Normal value in adult – 1200 ml.

Fig: Lungs Volumes and Capacities

Lung capacities

Lung capacities are a combination of two or more pulmonary volumes. The lung capacities are measurements of two or more volumes. The vital capacity (VC) measures the utmost amount of air that can be inhaled or exhaled during a respiratory cycle. It is the sum of the expiratory reserve volume, tidal volume, and inspiratory reserve volume.

Inspiratory capacity (IC = TV + IRV): Maximum volume of air which can be inspired from the resting expiratory level. It is the maximum amount of air that can fill the lung

Normal value (male) – 3500 ml.

Functional residual capacity (FRC = ERV+RV): It is the volume of air remains in the lungs at the end of normal expiration. It is the amount of air remaining in the lungs after a normal expiration.

Normal value (male) – 2300 ml.

Vital capacity (VC = IRV + TV + ERV): Maximum volume of air that can be expelled from the lungs by forceful effort following a maximal inspiration.

Normal value (male) – 4600 ml.

Total lung capacity (TLC = VC + RV): The volume of at contained in the lungs after a maximal inspiration.

Normal value (male) – 5800 ml.

Some of the air in the lungs does not contribute to gas exchange. Such air is situated in the anatomical dead space within bronchi and bronchioles—that is, outside the alveoli.