The digestive system is a complex series of organs that processes food. In order to use the food we eat, our body has to break the food down into smaller molecules that it can process.

Digestionoccurs in the gastrointestinal tract, the 20 to 30foot long tube extending from your mouth to your anus, plus a few other organs (like the liver and pancreas) that produce or store digestive chemicals. Whatever you eat flows through this system, but until it is absorbed through the intestinal tract, the nutrients in food are physically outside of your body.This is because the gastrointestinal tract functions like an internal skin and provides a barrier between whatever you ingest from the outside (external)world and your internal bloodstream and cells.

On average, food travels through the stomach in 1/2 to two hours, continues through the small intestine over the next two to six hours, and spends six to 72 hours in your large intestine before final removal by defecation.

The small intestine is a long, narrow, coiled tube extending from the stomach to the large intestine. This is the place where most digestion and absorption of food takes place. The small intestine of a human can be as long as six to eight meters long, depending on age and size of being. So much length can be compacted into so little space because of the nature of the small intestine; it is coiled and takes up less space, while maintaining it's enormous surface area.

The large intestine at the end of the human intestine and is wider but shorter than the small intestine. It measures approximately 1.5 meters in length and its primary function is to absorb water and electrolytes that have already passed unabsorbed through the small intestine.

For a diagram of the gastrointestinal track click here.