<P> The small intestine consists of the duodenum, jejunum and ileum . Inflammation of the small intestine is called enteritis, which if localised to just part is called duodenitis, jejunitis and ileitis, respectively . Peptic ulcers are also common in the duodenum . </P> <P> Chronic diseases of malabsorption may affect the small intestine, including the autoimmune coeliac disease, infective Tropical sprue, and congenital or surgical short bowel syndrome . Other rarer diseases affecting the small intestine include Curling's ulcer, blind loop syndrome, Milroy disease and Whipple's disease . Tumours of the small intestine include gastrointestinal stromal tumours, lipomas, hamartomas and carcinoid syndromes . </P> <P> Diseases of the small intestine may present with symptoms such as diarrhoea, malnutrition, fatigue and weight loss . Investigations pursued may include blood tests to monitor nutrition, such as iron levels, folate and calcium, endoscopy and biopsy of the duodenum, and barium swallow . Treatments may include renutrition, and antibiotics for infections . </P> <P> Diseases that affect the large intestine may affect it in whole or in part . Appendicitis is one such disease, caused by inflammation of the appendix . Generalised inflammation of the large intestine is referred to as colitis, which when caused be the bacteria Clostridium difficile is referred to as pseudomembranous colitis . Diverticulitis is a common cause of abdominal pain resulting from outpouchings that particularly affects the colon . Functional colonic diseases refer to disorders without a known cause, and include irritable bowel syndrome and intestinal pseudoobstruction . Constipation may result from lifestyle factors, impaction of a rigid stool in the rectum, or in neonates, Hirschprung's disease . </P>

What are the main diseases that affect the digestive system