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.
Muscle contractions also help generate body heat when needed, because of the large proportion of the body mass that it makes up. The active muscles release large amounts of heat and the blood transports heat to other tissues of the body for homeostasis. Other involuntary muscle contractions assist in the digestion of fluids and food. The primary function of muscle is to permit movement throughout the whole body. Without movement the purpose for living is nonexistent and futile. Why do we ...