Lower Human Torso
The esophagus is a hollow tube beginning at the very back of the pharynx (throat) and ending at the stomach. Its function is to transport swallowed food and liquid from the throat, through the chest into the stomach. It has little digestive function. In other words, it is not active in the breakdown or absorption of food.
The liver is the main warehouse for nutrients absorbed from the small intestine. Its job is to store, package and change these nutrients according to the needs of the body and then supply them to the blood stream for delivery to the various organs. The liver is a very large organ located in the upper right quadrant of the abdomen protected by the rib cage. It also produces bile which is stored in the gallbladder. Bile is necessary for the digestion and absorption of fat in the diet.
The stomach functions as a reservoir. It is a large, hollow organ and holds the food we eat. It secretes acid and some digestive enzymes which help begin the processes of digestion. It also acts as a churn to mix up food so that when the food is released through the valve at the end of the stomach ( called the pylorus), it is in a liquid or semi-liquid form ready to be digested and absorbed by the small intestine.
The gallbladder is a sac attached to the undersurface of the liver and is a storage reservoir for bile. Bile is made in the liver and passes down through a duct and up into the gallbladder. After one eats, the bile is released into the small intestine to mix with the food for better digestion and absorption of fat. The removal of the gallbladder by surgery, however, does not significantly interfere with the process of digestion or absorption.
The pancreas is an organ located immediately adjacent to the first part of the small intestine or duodenum. Its main function is to secrete digestive enzymes into the small intestine in order to help digest carbohydrates, protein and fat. It also secretes bicarbonate and water which neutralize the acid mixed with the food delivered into the duodenum from the stomach.
THE COLON and RECTUM
The colon receives water and undigested food products from the small intestine. Its function is to absorb water and to solidify the stool into a formed bolus which can be easily passed. If one ingests insufficient amounts of fiber in his diet, constipation may develop. Fiber is anything not digested or absorbed by the small intestine and which passes into the colon. Bran is one example of fiber.
THE SMALL INTESTINE
The small intestine is the major site for the digestion (breakdown of nutrients from food and liquid) and absorption (passage into the bloodstream) of nutrients so they can be used by the body. The small intestine is about 10 feet long, starts at the end of the stomach, and continues until it empties into the colon or large intestine. It is divided into 3 parts. The first section is the duodenum (approximately 12 to 18 inches in length) and is followed by the jejunum and then the ileum. In the duodenum, the acid mixed with the food delivered from the stomach is neutralized by water and bicarbonate which is secreted by the pancreas. This is important because the digestive enzymes and processes of digestion in the small bowel occur in a neutral, not acidic, environment.