Chapter 1: The Digestive System.
The overall function of the digestive system is to transfer the nutrients in food from the external environment to the internal environment, where they can be distributed to the cells of the body via the circulation. The cells of the body require adequate amounts of nutrients for their energy requiring processes and synthetic processes.
The digestive system (digestive tract) includes the mouth (oral cavity), the esophagus, the stomach, the gallbladder, the small intestine, the large intestine, and the anus. In addition, associated organs situated outside the digestive tract are essential for the digestive process. These are exocrine glands that secrete important digestive juices; they include salivary glands that produce saliva, the exocrine pancreas that secretes pancreatic juice, and the exocrine liver that produces bile (Figure 1.1).