The Gastrointestinal (GI) System is almost the same thing as a the Digestive System. The Gastrointestinal (GI) Tract consists of the mouth, esophagus, stomach, small intestine, large intestine (colon), rectum, and anus. The digestive system includes everything the Gastrointestinal (GI) Tract consists of plus the liver, pancreas, and gallbladder. The GI tract is where the food passes through from the mouth. It starts off in the mouth, then through the esophagus, stomach, small intestine, large intestine, and lastly the rectum.
The mouth is where the food is chewed and prepared to go through the esophagus. The esophagus then brings the broken down food into the the stomach to be stored. The stomach has gastric acid that helps food get broken down even more, although, the stomach does NOT absorb any of the food. Next, the food gets brought to the one of the three parts of the small intestine: Duodenum. In the duodenum, bile and liver enzymes are brought together with the food then is sent to the second part of the small intestine, the jejunum. The jejunum continues to further break down the food into more essential nutrients. Lastly, the ileum, the third part of the small intestine, absorbs the food products and liquids. The waste is then passed from the ileum to the large intestine, or colon. In the colon, waste products are stored until it is ready to exit the body through the rectum. Also the large intestine absorbs a little bit of water and electrolytes.
Now that you know the basics, the next couple pages will talk more about common pathologies of the GI system!