Alterations in the ratio of ventilation to perfusion, called the Image not available., will result in changes in the alveolar Image not available. are thus determined by the relationship between alveolar ventilation and pulmonary capillary perfusion.
Similarly, the mixed venous blood brings carbon dioxide into the lung and takes up alveolar oxygen. These concentration differences must be maintained by ventilation of the alveoli and perfusion of the pulmonary capillaries.Īlveolar ventilation brings oxygen into the lung and removes carbon dioxide from it. Diffusion of oxygen and carbon dioxide occurs passively, according to their concentration differences across the alveolar-capillary barrier. Gas exchange between the alveoli and the pulmonary capillary blood occurs by diffusion, as will be discussed in the next chapter.