1 Chemically, ATP is an adenine nucleotide bound to three phosphates. 2  There is a lot of energy stored in the bond between the second and third phosphate groups that can be used to fuel chemical reactions. 3  When a cell needs energy, it breaks this bond to form adenosine diphosphate (ADP) and a free phosphate molecule.
calf muscle pump. calf muscle pump. an action of the calf (soleus) muscles in which the muscles contract and squeeze the popliteal and tibial veins, forcing the blood in those veins to move upward toward the heart. Also called soleus pump.
Remember, the purpose of a fuel pump is twofold: 1  It pushes or pumps fuel from the gas tank to the fuel injector or carburetor.  It creates the proper amount of pressure to ensure that the right amount of fuel will be delivered to the engine, regardless of external conditions.