Human Digestion Essay

The salivary glands are the first to react in the digestive process, which are usually triggered by either the sight or the smell of food. Food enters the digestive tract through the mouth where the teeth, tongue, and salivary glands help moisten and break down the food within minutes. The food then becomes something called a bolus, which will travel through the pharynx, then through the esophagus, and into the stomach. As the food travels through the pharynx the epiglottis is in place to prevent food from entering the lungs. Once the bolus enters the stomach it is broken down with acid secretions. The food is partially digested within the stomach. The bolus then becomes chyme (a semiliquid food). Chyme usually leaves the stomach during a time frame of 2-6 hours. The small intestine is where most of the digestion and nutrient absorption takes place with the help of secretions from the liver, gallbladder, and pancreas. The small intestine consists of three parts: the duodenum, the jejunum, and the ileum. Anything that is not absorbed in the small intestine then enters the large intestine travelling through the sphincter. The sphincter prevents any of the remaining food from re-entering the small intestine. The large intestine is made up of two major parts: the colon and the rectum. The colon aids in the absorption of leftover water, vitamins, or minerals. Anything left over after this process is considered waste product (feces) and is then excreted from the body via the anus, which  is attached to the colon. Reference Human Digestion Activity. Retrieved August 21, 2009 from http://corptrain.phoenix.edu/axia/sci241/sci241-digestivetract.html