Hello maya1LTIN,
I think what you are asking is how does Cellular Respiration work? Here is a simplified explanation of the process:
The food you eat turns into energy, as you may already know. The food is broken down into smaller parts including amino acids (from proteins), fatty acids (from fats), and carbohydrates/glucose (from sugars). These are then broken down by the body and their energy is released to cells that need it. The glucose, for instance is pumped into the cell membrane and transported to the mitochondria of the cell, where it is further broken down to create energy (ATP).
Cellular respiration is the breakdown of nutrients (such as sugars, or glucose) to produce energy that is distributed and used throughout the body. This process occurs in the Mitochondria of the cell. After ATP is produced (through cellular respiration, which includes Glycolysis, Krebs Cycle, and Electron Transport reactions), the energy (aka ATP) is released from the mitochondria through (proton or other) pumps into the cell. All cells have this process, so ATP is produced in muscle cells, nerve cells, etc. Once the ATP is released from the Mitochondria, it is used in the cell to initiate actions within the cell. For instance in a muscle cell, ATP bonds with a protein called Myosin, which causes an action of releasing a muscle cell. The reactions of the breakdown and creation of ATP in a muscle cell are what makes a muscle work.
Here are some resources to better explain these ideas:
http://hyperphysics.phy-astr.gsu.edu/hb ... elres.html
http://www.cliffsnotes.com/study_guide/ ... 24992.html
http://www.montana.edu/craigs/How%20Muscles%20Work.htm
http://www.soundformulas.com/page9.html
Does this help answer your question?
