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.
The heart is a muscle. It has four chambers that pump blood. The upper two chambers are called the atria and the lower two chambers are called the ventricles.. The heart is really two pumps that work together to move blood through the body.The right-sided pump fills with blood returning from the body and pumps it to the lungs to receive oxygen.This right-sided pump is a thinner muscle than the left-sided pump because it only has to pump blood to the lungs. The left side of the heart receives blood from the lungs and pumps it out to all parts of the body.he heart is a muscle. It has four chambers that pump blood. The upper two chambers are called the atria and the lower two chambers are called the ventricles.. The heart is really two pumps that work together to move blood through the body.