The Intestinal System

The intestinal system consists of hollow organs, including the oesophagus, stomach, small bowel, and large bowel, that hold and move nutrients through your body.

The intestinal system is part of the overall digestive system.

The stomach, which receives food from the oesophagus, is located in the upper left quadrant of the abdomen. The stomach is divided into the fundic, cardiac, body, and pyloric regions. The lesser and greater curvatures are on the right and left sides, respectively, of the stomach.

The small intestine extends from the pyloric sphincter to the ileocecal valve, where it empties into the large intestine. The small intestine finishes the process of digestion, absorbs the nutrients, and passes the residue on to the large intestine.

The small intestine is divided into the duodenum, jejunum, and ileum. The small intestine follows the general structure of the digestive tract in that the wall has a mucosa with simple columnar epithelium, submucosa, smooth muscle with inner circular and outer longitudinal layers, and serosa. The absorptive surface area of the small intestine is increased by plicae circulares, villi, and microvilli.

The large intestine is larger in diameter than the small intestine. It begins at the ileocecal junction, where the ileum enters the large intestine, and ends at the anus. The large intestine consists of the colon, rectum, and anal canal.

The wall of the large intestine has the same types of tissue that are found in other parts of the digestive tract but there are some distinguishing characteristics. The mucosa has a large number of goblet cells but does not have any villi. The longitudinal muscle layer, although present, is incomplete. The longitudinal muscle is limited to three distinct bands, called taeniae coli, that run the entire length of the colon.

Unlike the small intestine, the large intestine produces no digestive enzymes. Chemical digestion is completed in the small intestine before it reaches the large intestine. Functions of the large intestine include the absorption of water and electrolytes and the elimination of faeces.