August 1, 2012
Human Digestion Summary
The digestive system provides two main functions, absorption and digestion. The main part of the digestive system is the gastrointestinal tract also referred to as the GI tract. This runs all the way from the mouth to the anus, about thirty feet long. The GI tract is made up of the mouth, pharynx, esophagus, stomach, small intestine, large intestine and anus. The transit time is the amount of time it takes for food to pass through the length of the gastrointestinal tract. Transit time normally takes any where from twenty-four hours to seventy-two hours. The time it takes is affected by the composition of the diet, physical activity, emotions, medications and illness. Digestion as most know starts in the mouth. Your food is ground up by your teeth and when you are chewing your glands make saliva. Saliva is constantly produced but more is made when we are eating. The saliva softens and moistens the food in our mouth. Enzymes in the saliva help break down food so it is easier to swallow. After the mouth the food then moves through the esophagus to the stomach. By the time the food reaches the stomach it is already made into fat, protein, starch and sugar. The stomach muscles contract and relax about three times a minute. This kind of churns the food mixing it with the powerful digestive juices. This process turns food into a liquid called chyme. The chyme then moves through the pyloric sphincter into the small intestine. The small intestine is an important part of the digestive process. Actually most of the digestion process occurs here. The first part of the small intestine is called duodenum and is about eight to ten inches long. Chemicals here neutralize the acid so the chyme can continue in the digestive system. Digestive juices from the liver and pancreas enter to mix with the liquid food. These finish breaking down fats, proteins, starches...