The answer is: "dopamine" .
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The respiratory system works directly with the circulatory system to provide oxygen to the body. Oxygen taken in from the respiratory system moves into blood vessels that then circulate oxygen-rich blood to tissues and cells.
Some molecular studies point to amphibians descending from the lung fish, the Diponi.
Under the class Amphibia, amphibians are tetra-pod, cold blooded vertebrates without having scales. Protein is produced by the special skin of Amphibians.
Lung fish belong to the subclass of Diponi, these are living air breathing species.
Each somatic cell has 46 cells and 24 pairs. Once the cell replicates it will have the same amount of cell (46) and the same amount of pairs(24).
