The large intestine carries out the function of absorption of water and electrolytes as well as storing waste until it can be expelled. It is also responsible for maintaining water balance and some absorption of vitamins such as vitamin K. The mixture of remaining food and intestinal juices called chyme in the colon is devoid of almost all nutrients and water; it consists of primarily the undigested food with some amount of water and electrolytes.

The small intestine is a long tube that is approximately 18 feet long (6 meters). The small intestine is called small because the diameter or the width of the tube is much less than the large intestine. The parts of the small intestine include the duodenum, jejunum and the ileum. The duodenum is a segment of intestine between the stomach and the jejunum that is very active in digestion where many different enzymes mix from the stomach, liver, gallbladder and pancreas.

The duodenum lies at the beginning of the small intestine. Together with the jejunum, and the ileum it forms the small intestine. It is connected to the stomach above and the jejunum below it. When food enters the duodenum, there are multiple feed-back pathways and nervous reflexes that will affect how fast the stomach empties as well as the secretion of other hormones.

One of the functions of the gallbladder is to concentrate the bile produced by the liver. Mainly by removing water, the bile is reduced from a fifth to a tenth of its original volume until reaching the maximum capacity of the gallbladder at about 50 milliliters. This concentration is a kind of balancing act. If the gallbladder doesn’t concentrate the bile, then there may not be enough active ingredients to break down a heavy load of fat, resulting in digestive problems. If the gallbladder performs too much concentration, the lack of water may stimulate the formation of gallstones around impurities in the high saturation of cholesterol.