![]() ![]() ![]() Then the person expires through a rapidly recording nitrogen meter, which makes the record shown in the figure. ![]() Some oxygen also mixes with the alveolar air but does not completely replace this air. Thisįills the entire dead space with pure oxygen. In making this measurement, the subject suddenly takes a deep breath of oxygen. A simple methodfor measuring dead space volume is demonstrated by the graph in Figure 37–7. Therefore, the dead space is very disad-vantageous for removing the expiratory gases from the lungs. On expiration, the air in the dead space is expired first, before any of the air from the alveoli reaches the atmosphere. This air is called dead spaceair because it is not useful for gas exchange. Some of the air a person breathes never reaches the gas exchange areas but simply fills respiratory pas-sages where gas exchange does not occur, such as the nose, pharynx, and trachea. “Dead Space” and Its Effect on Alveolar Ventilation The rate at which new air reaches these areas is called alveolarventilation. These areas include the alveoli, alveolar sacs, alveolar ducts, and respiratory bronchioles. The ultimate importance of pulmonary ventilation is to continually renew the air in the gas exchange areas of the lungs, where air is in proximity to the pulmonary blood. ![]()
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