PNB 2265 Lecture Notes - Lecture 18: Pulmonary Edema, Perfusion, Chronic Obstructive Pulmonary Disease
6 Mar 2017
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Alveolar - blood gas exchange ( external respiration) Movement of gases across respiratory membrane affected by: Amount of gas reaching specific alveoli (ventilation) Local controls of pulmonary arteriolar diameter which are exactly. Opposite those you learned for control of systemic arterioles. Gas solubilities (which gas is more soluble?) Thickness of respiratory membrane - normal = 1 micron. Surface area for exchange - normal = 140 m^2. Biconcave disk shape of rbc facilitates transport. Diseases such as emphysema impede gas exchange. Partial pressure and diffusion gradients are reversed. Po2 values for systemic arterial blood (about 100 mm hg) and tissues (40 mm hg) Pco2 values: systemic arterial blood (40 mm hg) and tissues (46 mm. Exchange is rapid and complete (to equilibrium) Small amount dissolved in plasma (giving our po2) Hb greatly increases the amount of o2 that can be carried in the blood. Po2 determines whether oxygen binds to hb or is released from hb.
