Step Two of the Digestive System
The esophagus lies right behind the windpipe. It is the part that connects the mouth to the stomach. The esophagus is about 10 inches long. The walls of the esophagus are made up of many layers. The outer most layer is called serosa. Underneath the serosa there are many layers of muscles. After the muscular layers, there is a layer of tough blood vessels and nerves called submucosa. The innermost layer is called mucosa which is coated with slimy liquid called mucus (Kopf-Maier, 2004). The food that comes to the esophagus does not move through it automatically. It is pushed down by the muscles that relax and contracts to push the food down. The muscles move in waves and this process is called peristalsis. The whole digestive system has almost the same muscle structure and peristalsis waves. At the end of the esophagus, there is a ring of muscles called esophageal sphincter. This muscle is tightly shut until the food comes down the esophagus. Then these muscles relax to allow the food to enter the stomach. When this muscle does not close properly, it results in burning sensation (Ballard, 1997).
The esophagus lies right behind the windpipe. It is the part that connects the mouth to the stomach. The esophagus is about 10 inches long. The walls of the esophagus are made up of many layers. The outer most layer is called serosa. Underneath the serosa there are many layers of muscles. After the muscular layers, there is a layer of tough blood vessels and nerves called submucosa. The innermost layer is called mucosa which is coated with slimy liquid called mucus (Kopf-Maier, 2004). The food that comes to the esophagus does not move through it automatically. It is pushed down by the muscles that relax and contracts to push the food down. The muscles move in waves and this process is called peristalsis. The whole digestive system has almost the same muscle structure and peristalsis waves. At the end of the esophagus, there is a ring of muscles called esophageal sphincter. This muscle is tightly shut until the food comes down the esophagus. Then these muscles relax to allow the food to enter the stomach. When this muscle does not close properly, it results in burning sensation (Ballard, 1997).