Things don't always look like the way they work, and metaphors using the familiar are helpful in explaining the complex (Richard Wurman: "People only understand something relative to something they already understand). The heart-lungs-body route is actually very much like a transit network. The vocabulary used in this diagram is an homage to Harry Beck's London Underground map. It has two advantages over anatomical, especially dimensional, illustrations: 1) the right pulmonary vein is clearly visible; 2) moving the aortic arch to the bottom of the heart keeps the "traffic" moving in one direction and reduces the complexity of the heart's actual anatomy.
