The digestive tract (digestive system) is like a long tube that extends from the mouth to the anus. When we eat, the food passes through the esophagus and down into the stomach, where the gastric (digestive) juices then break down the food into a consistency similar to porridge. The partially digested food then passes through the small intestine. The food is further broken down in the small intestine so that the nutrients (the useful parts of the food) can be absorbed into the bloodstream. The waste products from this process – the liquid and undigested parts of the food – are then advanced to the colon (also called the large intestine). The colon absorbs the liquid and the remaining waste products form solid feces. They collect in the last part of the colon and in the rectum until they are excreted through bowel movements. Crohn’s disease can cause ulceration and chronic inflammation of the gastrointestinal tract, which in turn makes it difficult for the body to adequately digest food, absorb nutrients and excrete waste products. Crohn’s disease can affect any part of the GI tract, but most often occurs in the ileum (the last part of the small intestine) and the colon. Ulcers are usually segmental in distribution, with normal intestinal tracts between lesions. A single ulcer may be small, only a few centimeters, or it may extend for a considerable distance along the digestive tract. In addition to affecting the superficial layers of the intestinal mucosa, Crohn’s disease may also involve the deeper intestinal wall. What are the main symptoms of Crohn’s disease? Symptoms of Crohn’s disease range from mild to severe and vary from person to person. Symptoms may also change over time, from periods when you are in good health and have few or no symptoms (remission) to periods when symptoms are more active (relapses or “flare-ups”). This is a very individual disease, and some people may stay well for a long time, even for years, while others will have frequent flare-ups. Your symptoms may also depend on which part of the digestive tract Crohn’s disease occurs. However, the most common symptoms of a sudden attack are as follows: – abdominal pain and diarrhea. Sometimes the diarrhea may be mixed with mucus, pus or blood. - Tiredness and fatigue. This can be caused by the disease itself, sudden attacks or weight loss associated with surgery, anemia (see below), or simply lack of sleep (needing to get up frequently at night due to pain or diarrhea). - Feeling unwell throughout the body. Some people may experience an increased body temperature and feel feverish. - Mouth ulcers. - Lack of appetite and weight loss. Weight loss may also be caused by inflammation of the digestive tract that prevents the body from absorbing nutrients from the food you eat. - Anemia. You are more likely to become anemic if you bleed, eat less, or have poor nutrient absorption. Anemia can also make you feel very tired.