The Human Digestive Process

Digestion is the process in which the body breaks down food into particles that can be used for nourishment. The stomach is not the only organ involved in the digestion process. A series of organs comprise the human digestive tract, including the mouth, esophagus, stomach, small intestines, liver and large intestine. Each organ in the digestive tract plays an integral part in the digestive process. The food enters the mouth, where it is masticated and prepped for digestion. The mouth is comprised of multiple features that contribute to the beginning process of digestion. These features include the lips, cheeks, roof of the mouth, floor of the mouth, gums, teeth, tongue, and salivary glands (Human Digestive System). The lips, cheeks, roof of the mouth, and floor of the mouth are primarily used for containment of food. The gums secure the teeth. The teeth are used to cut and grind food. The tongue moves the food around in the mouth, and the salivary glands secrete a digestive fluid. Once the mastication process has been completed, the food is swallowed and it enters the esophagus. The esophagus transports liquids and food from the back of the throat to the stomach. The esophagus is the simplest of the organs in the digestive track. It is comprised of two types of muscles: striated muscle and smooth distal muscles. This organ is bound by the upper and lower sphincters. During swallowing the muscles relax moving the larynx forward and assisting in the routing of food (The Esophagus). After the food passes through the esophagus, it transitions into the stomach where absorption of food begins. The stomach breaks down food both physically and chemically creating smaller pieces. It does this through muscular movement and hydrochloric acid. The acid also destroys bacteria and other dangerous pathogens. It also changes pepsinogen, which is produced by cells lining the stomach, into pepsin. Pepsin is used to break down protein and turns it in to peptide chains. These chains are made of amino acids. This is important as the small intestine absorbs amino acids. Your stomach also contains a variety of chemicals used to break down different vitamins, peptides and fats (What Does the Stomach Do?). After the food is done processing in the stomach it moves to the small intestine. The small intestine is the organ in the body where the majority of the nutrients from ingested food are absorbed. It is comprised of three parts: the duodenum, the jejunum and the ileum. Additionally the small intestine totals to roughly 18 feet in length. The duodenum is the first part of the small intestine. It is where different enzymes mix from the stomach, liver, gallbladder and pancreas. The jejunum is the second part of the small intestine. It is covered with hair-like projections called villi. The villi are critical in the absorption of nutrients such as proteins, carbohydrates, amino acid, sugar, fatty acid particles, vitamins, minerals, electrolytes and water. The ileum is the last part of the small intestine. It absorbs vitamin B12, other water soluble vitamins, bile salts, and nutrients that were not absorbed in the jejunum. The ileum connects to the large intestine (“Your small intestine and digestion”). The liver plays an integral part of the digestive system through its production of bile, toxin metabolism and blood sugar regulation. Bile is used to break down fats and allows them to be more easily absorbed by the intestine. The toxin metabolism filters out toxins that would otherwise enter the body and destroy the tissues of the digestive track and other organs. Finally, the liver helps to regulate the bloods sugar level. The liver will take excess sugar and convert it to glycogen. When the sugar levels are low the glycogen is converted back into glucose, which brings the sugar level up to normal (How Does the Liver Function in the Digestive System?). The final process of the digestive is the large intestine. It has three parts: the cecum, the colon, and the rectum. The cecum is a pouch at the beginning of the large intestine. This area allows food to pass from the small intestine to the large intestine. The colon, where fluids and salts are absorbed, extends from the cecum to the rectum. The last part of the large intestine is the rectum, which is where feces (waste material) is stored before leaving the body through the anus. The main job of the large intestine is to remove water and salts (electrolytes) from the undigested material and to form solid waste that can be excreted. Bacteria in the large intestine help to break down the undigested materials. The remaining contents of the large intestine are moved toward the rectum, where feces are stored until they leave the body through the anus as a bowel movement (What Does the Large Intestine Do?).

Works Cited
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The Esophagus. (n.d.). In About.com. Retrieved from http://biology.about.com/library/organs/blpathodigest5.htm 9 June 2013
What Does the Stomach Do?. (n.d.) In Were You Wondering online. Retrieved from http://www.wereyouwondering.com/what-does-the-stomach-do/ 9 June 2013
Your small intestine and digestion. (n.d.). In laparoscopic.md. Retrieved from http://www.laparoscopic.md/digestion/intestine 9 June 2013
How Does the Liver Function in the Digestive System?. (n.d.) In livestrong.com. Retrieved from http://www.livestrong.com/article/29986-liver-function-digestive-system/ 9 June 2013
What Does the Large Intestine Do?. (n.d.) In news-medical.net. Retrieved from http://www.news-medical.net/health/What-Does-the-Large-Intestine-Do.aspx
9 June 2013