This particular tutorial is being inserted because of the progression of the carbohydrate lessons. Please note, however, that it is not just carbohydrates that produce the glucose that results in energy. This will be covered in upcoming tutorials.
This lesson is better understood by going back and reading the Your Metabolism lesson.
Mainly, carbohydrates are used to provide the body with energy, and this mostly in the form of glucose after the carbohydrate has been broken down (as seen in some previous lessons). Once the glucose is in the cells, cellular respiration produces carbon dioxide, water, and ATP. For the sake of this tutorial, consider ATP (adenosine triphosphate) as the energy needed to help our body operate.
ATP is a molecule. It occurs when a glucose molecule with 6 carbon atoms is split in half. This split creates 2 molecules of ATP. This process is called glycoloysis. The key is that the process of splitting the molecule also doesn't need oxygen to work.
If cellular respiration totally dismantles the glucose molecule, it produces much more ATP. Cellular respiration is when oxygen is used to dismantle the molecules.
The body can store glucose molecules when they are linked together. This is called glycogen. It is stored in muscle tissue and liver tissue. If the body needs more glucose, these stores are opened, the glucose molecules are broken down, and the process repeats itself. The body doesn't store a lot of glycogen, which is one reason why breakfast is so important.