Key Points

• O2 moves from the atmosphere to tissues by a series of convective (bulk flow) and diffusive transport steps, which decrease Po2 at each step.

• Alveolar Pco2 is inversely related to alveolar ventilation at any given metabolic rate. Physiologic dead space is the functional difference between total ventilation and effective ventilation of the alveoli.

• O2 diffusion from alveolar gas to pulmonary capillary blood is effective at equilibrating alveolar and arterial Po2 in normal individuals under most conditions.

• O2 delivery by the cardiovascular system depends on cardiac output and the arterial-venous O2 difference. The shape of the blood-O2 equilibrium curve is advantageous for O2 transport to tissues.

• The pathway for O2 diffusion is longer in tissues than in the lung, so Po2 differences between blood and tissue are much larger than the blood-gas Po2 difference in the lung.

• There are four main causes of arterial hypoxemia. Hypoventilation differs from other causes of hypoxemia because it does not increase the alveolar-arterial Po2 difference, and it can occur in patients with normal lungs.

• Diffusion limitation can result from thickening of the blood-gas barrier in lung disease, but oxygen breathing rapidly alleviates this form of arterial hypoxemia.

Essential Medical Physiology, Third Edition

Get Rid of Gallstones Naturally

Get Rid of Gallstones Naturally

One of the main home remedies that you need to follow to prevent gallstones is a healthy lifestyle. You need to maintain a healthy body weight to prevent gallstones. The following are the best home remedies that will help you to treat and prevent gallstones.

Get My Free Ebook

Post a comment