For gas exchange to be efficient there must be a close match of ventilation & perfusion in the lungs. This video offers an overview of the process of ventilation perfusion matching, using beautiful, scientifically accurate 3D visualisation & digital story-telling. We take a look inside the human body to follow the path of air breathed in, right down to the alveolar capillaries, to see what occurs to the partial pressure of oxygen (PO2) & the partial pressure of carbon dioxide (PCO2) when ventilation is low or high relative to perfusion. This video is designed to facilitate your understanding of this specific area of respiratory physiology & was released on the App Store Oct 2011. We welcome your feedback & suggestions re: future topics you would like to see 3Dme produce for the upcoming App Video Catalogue. This video won a 2010 New York Global Finalist Award.