Science, Maths & Technology
Blood and the respiratory system
...De-oxygenated blood from the systemic tissues is carried to the lungs by the pulmonary arteries and has a PO2 of 40 and a PCO2 of 45 millimetres of mercury. As the blood enters the alveoli, the higher PO2 in the lungs drives oxygen shown in red out of the alveoli and into the blood. At the same time, the slightly higher PCO2 in the blood drives carbon dioxide, shown in...