Each time the glucose molecule disassembles, energy is not simply released into the medium.
Energy is transferred to other molecules (called ATP - Adenosine Triphosphate), which will serve as temporary energy reservoirs, "batteries" that can release "pills" of energy wherever they are.
In cell cytoplasm, a soluble substance commonly known as adenosine diphosphate, ADP. Also common are inorganic phosphate free soluble radicals (which we will symbolize by Pi), monovalent anions of ortho-phosphoric acid. Each time energy release occurs in aerobic respiration, this energy binds inorganic phosphate (Pi) to ADP, generating ATP.. Because ATP is also soluble, it spreads throughout the cell.
The binding of ADP with phosphate is reversible. So whenever energy is needed to do any work on the cell, some ATP molecules are converted to ADP + Pi and the released energy is used by the cell. ADP recharge occurs every time energy is released from glucose disassembly, which occurs in aerobic respiration or fermentation.
The ATP Structure
ATP is a nucleotide-derived compound where adenine is the base and sugar is ribose. The adenine plus ribose set is called adenosine. The union of adenosine with three phosphate radicals leads to the adenosine triphosphate compound, ATP. The bonds that keep the second and third phosphate radicals trapped in ATP are highly energetic (they release about 7 Kcal / mol of substance).
Thus, each time the third phosphate disconnects from the assembly, energy is released that holds it together with ATP. It is this energy that is used when we walk, talk, think or do any cellular work.