Brief introduction of lung in English
Lung is the basic respiratory organ of animals that breathe air, including most quadrupeds, some fish and some snails. The most primitive animals with lungs are lungfish (vertebrates) and lungfish (invertebrates). In mammals and more complex life forms, two lungs are located in the chest on both sides of the heart. Their main function is to transport oxygen from the atmosphere to the blood and release carbon dioxide from the blood to the atmosphere. This gas exchange is completed in the mosaic of special cells, which form millions of tiny air sacs with extremely thin walls, called alveoli.