avtavr:The respiratory system within the lungs — illustrated here by a model made from a resin cast
avtavr:The respiratory system within the lungs — illustrated here by a model made from a resin cast — consists of a closely interlinked system of air passages, arteries and veins. Deoxygenated blood, shown in blue, is pumped from the heart through a treelike arrangement of pulmonary arteries and arterioles until it flows through capillaries in and around the alveoli, which are the terminations of the bronchial “tree”, shown in white. Oxygen is absorbed and carbon dioxide is released before the blood, now oxygenated and shown in red, returns through a similar arrangement of pulmonary veins to the heart. The model is seen from the front so the left side of the chest appears on the right. The heart lies in the left side of the chest and, to accommodate it, the two-lobed left lung is smaller than the three-lobed right lung.© Science Source/Science Photo Library -- source link
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