Stale air from the lungs and fresh air from the anatomical dead space After an inhalation, the anatomical dead space (the ~150 ml air in the trachea and bronchi that has not reached the alveoli) contains air from the atmosphere, albeit now saturated with water vapour, that has not had its oxygen content depleted by gas exchange in the alveoli and hence is “fresh”. This air, plus some “stale” air from the alveoli, but with some residual oxygen, is exhaled into the recipient’s lungs.

---

Related posts

Which structures are called bronchioles? Blood entering the capillaries of the alveoli has dissolved CO₂ at 46 mm Hg and is separated from air in the alveoli, which contains CO₂ at a partial pressure of 40 mm Hg, by the respiratory membrane. What will be the concentration of dissolved CO₂ of the blood capillaries leaving the alveoli? Mt. Everest “base camp” is located 5300 m above sea level. Here, the atmospheric pressure is 403 mmHg (rather than 760 mmHg at sea level), and the oxygen partial pressure in atmospheric air at this altitude is about 79 mmHg. What is the likely value for dissolved oxygen concentration in arterial blood for someone at base camp? Which of the following buffer systems of the body is affected by the action of the lungs? Which molecule or ion dissolved in blood is able to stimulate the central chemoreceptors of the brain’s respiratory centre? Which of the following lists the components of the respiratory membrane? If the partial pressure of oxygen in the air contained in the alveoli of the lungs is 14 kPa, then the partial pressure of oxygen dissolved in the alveolar fluid will be: