2.2.1 “Dead space”

Of the 500 ml of air inhaled in normal inspiration, not all reaches the respiratory membranes in the lungs in the alveoli, a proportion of the air inhaled and exhaled is ”standing” in the oral cavity, pharynx, larynx and trachea and upper bronchi and bronchioles. This area where the air does not participate in gas exchange is called the ”dead space”, and it represents a volume of about 150 ml.

This means that air which is available for gas exchange (out of the 500 ml’s inspired) is equivalent to about 350 ml (the inspiratory volume minus the dead space volume).

Fig.9