Glucose and oxygen are two vital substances for the body.
With glucose "fuel", the body produces heat, the muscles will shrink and brain is developing its main function.
The brain needs 140g daily and this is also the only substance the brain "eats".
From here it is transported, with blood, to all cells. As to be transformed into energy, that is to penetrate the cells in order to be burned, glucose requires the action of a hormone, called insulin.
How glucose becomes energy?
The main store of glucose is the liver.
When there is not enough insulin, because the pancreas does not produce it,glucose accumulates in the blood, at a high level, instead of being used by cells. From here, the problems start.
I would expect that glucose would produce heat if one were to add a little sulfuric acid.
On the other hand, if one means to ask how do cells convert glucose into energy, then one would say by cellular respiration, which is a process by which enzymes break the chemical bonds in the glucose molecule and produce ATP or other forms of energy.
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