It is also at this point that other organs begin to play a major role in the digestive process. The pancreas, located adjacent to the small intestine, secretes several enzymes that variously break down carbohydrates much further than they were broken down in the mouth or the proteins that began to met their demise in the stomach (NDDIC 2008). The liver produces a bile that breaks down fats and makes the constituent parts into small enough droplets that they can be suspended in water and utilized in chemical processes in the body (NGS 2010). All of this digestion takes place in the duodenum.
The small intestine continues, however, and throughout the entire small intestine are countless villi, or little finger-like hills that greatly increase the inner surface area of the smooth-muscled tube that is the small intestine (Discovery 2000). It is through the cells of these villi that the nutrients, once broken down into smaller parts by the digestive processes and enzymes, are passed through to the rst of the body (Discovery 2000). Specifically, active chemical transport is used to carry carbohydrate and protein-based nutrients through the cell walls of the intestinal villi and lining, where they are eventually passed into the bloodstream (Enchanted Learning 2010). Similar processes take place with the components of fatty nutrients, but it is the lymph system that transports these molecules (Enchanted Learning 2010).
After passing through the entirety of the small intestine, the leftover material passes into the large intestine or colon. It is here that a great deal of the water used to lubricate the digestive process — generally in the form of mucous and other substances that have a high water content — is reabsorbed into the body, along with certain other mineral nutrients that might not have been absorbed through the small intestine (NGS 2010).
There are also bacteria living in the colon that produce necessary nutrients for the body, and these are also absorbed through the wall of the large intestine (NDDIC 2008). After passing through all of this, what is left is generally waste, and it is pushed through the body and eventually defecated (NDDIC 2008). Feces actually consist of nearly seventy-five percent water despite the massive reabsorption that occurs prior to defecation, and the remaining one quarter is usually comprised of one third dead bacteria, with the remaining two thirds of a quarter actually consisting of unused substances from ingested foods (Discovery 2000). This demonstrates the efficiency the body is at drawing nutrients from the food sources it is given.
Without digestion, nothing else in the body would be able to occur; there simply wouldnt be the energy or the specific molecules and chemicals necessary to carry out bodily functions. Though there are many parts to the digestive system, it manages to accomplish its job with a great deal of efficiency and efficacy, carefully breaking down food and pulling out all available nutrients. Its reliance on other systems for delivery assistance also demonstrates the interconnectivity of the human body.
Discovery. (2000). “Your digestive system.” Accessed 30 September 2010. http://yucky.discovery.com/flash/body/pg000126.html
Enchanted Learning. (2010). “Human digestive system.” Accessed 30 September 2010. http://www.enchantedlearning.com/subjects/anatomy/digestive/
NDDIC. (2008). “Your digestive system and how it works.” Accessed 30 September 2010. http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/
NGS. (2010). “digestive system.” Accessed 30 September 2010. http://science.nationalgeographic.com/science/health-and-human-body/human-body/digestive-system-article.html.