The first step of digestion begins at the mouth, where the food enters the mouth. Saliva is secreted from the salivary glands. The saliva contains enzymes such as Ptyalin, which starts sugar digestion. The enzymes also provide lubrication to help in the chewing and swallowing of the food. The food then goes down the esophagus and into the stomach, where the next step of digestion takes place.

In the stomach, a mixture of hydrochloric acid and Pepsin, which is secreted by the stomach wall, liquefies the food. At the same time, a substance called intrinsic factor binds Vitamin B in food and various gastric enzymes, such as Pepsin (which begins protein digestion), which are secreted by the stomach wall. Secretions of mucus protect the stomach from its digestive enzymes. The food is then mixed in the stomach, turning it into chyme(digested food). The muscular pumping mot

From the duodenum, the chyme passes to the jejunum and ileum, where tiny finger-like objects called villi, cover the walls. These villi start the absorption of food. During the absorption, food molecules enter the blood stream through the walls of the intestine. From the small intestine, the digested products travel to the liver. Liver cells filter the blood of any harmful substances such as alcohol and ammonia.

A peptic ulcer is an open sore in the mucus membrane of the stomach. While and ulcer is developing, part of the surface tissue breaks down, dies, and becomes inflames. There are two types of peptic ulcers. The first is the duodenal, which forms in the duodenum. Gastric ulcers develop in the stomach. The pepsin, located in the stomach, can eat through the lining of the stomach and the duodenum. Pepsin wouild not normally eat through the lining of the stomach and duodenum because of mucus which is normally secreted to protect the walls of them. Most peptic ulcers cause pain in the upper part of the abdomen. Peptic ulcers occur usually when the stomach is empty. People can reduce the risk of ulcers by not smoking and drinking alcoholic beverages.

Diarrhea is another disorder in the digestive system. It has symptoms of loose and frequent bowel movements. Nausea, loss of bowel control, and abdominal cramps, frequently come along with diarrhea. The most frequent cause of diarrhea is infection by viruses, bacteria, or protozoans. Treatment of diarrhea consists primarily of replacing lost body fluids and salts.

Colon cancer is the common name for an uncontrolled division of cells in the large intestine. Many doctors use the term colorectal cancer, because the disease affects the main part of the large intestine, the colon, and the last part, the rectum. Colon cancer is one of the most common cancers in North America and Europe. In its early stages, cancer in

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