The mentioned video is exactly what you need in order to gain a concise knowledge about the partial pressures of Oxygen and Carbondioxide and their changes. Further light is also shed on Arterial and Venous Blood, and on their different aspects. Timeline: 00.00 Introduction 00:42 Partial Pressure of Gases (Inspired and Expired Air) 02:27 Gaseous Exchange in the lung 03:15 Partial Pressure of Gases in Pulmonary Circulation 06:30 Partial Pressure of Gases in Systemic Circulation 08:30 Arterial Blood Gas 10:48 Mixed Venous Blood