This collaboration of two physiologists and a gastroenterologist provides medical and graduate students, medical and surgical residents, and subspecialty fellows a comprehensive summary of digestive system physiology and addresses the pathophysiological processes that underlie some GI diseases. The textual approach proceeds by organ instead of the traditional organization followed by other GI textbooks. This approach lets the reader track the food bolus as it courses through the GI tract, learning on the way each organ's physiologic functions as the bolus directly or indirectly contacts it. The book is divided into three parts: (1) Chapters 1-3 include coverage of basic concepts that pertain to all (or most) organs of the digestive system, salivation, chewing, swallowing, and esophageal function, (2) Chapters 4-6 are focused on the major secretory organs (stomach, pancreas, liver) that assist in the assimilation of a meal, and (3) Chapters 7 and 8 address the motor, transport, and digestive functions of the small and large intestines. Each chapter includes its own pathophysiology and clinical correlation section that underscores the importance of the organ's normal function.

This collaboration of two physiologists and a gastroenterologist provides medical and graduate students, medical and surgical residents, and subspecialty fellows a comprehensive summary of digestive system physiology and addresses the pathophysiological processes that underlie some GI diseases. The textual approach proceeds by organ instead of the traditional organization followed by other GI textbooks. This approach lets the reader track the food bolus as it courses through the GI tract, learning on the way each organ's physiologic functions as the bolus directly or indirectly contacts it. The book is divided into three parts: (1) Chapters 1-3 include coverage of basic concepts that pertain to all (or most) organs of the digestive system, salivation, chewing, swallowing, and esophageal function, (2) Chapters 4-6 are focused on the major secretory organs (stomach, pancreas, liver) that assist in the assimilation of a meal, and (3) Chapters 7 and 8 address the motor, transport, and digestive functions of the small and large intestines. Each chapter includes its own pathophysiology and clinical correlation section that underscores the importance of the organ's normal function.

The gastrointestinal mucosal defense system serves to minimize mucosal injury by either ingested or endogenously produced noxious substances. The mucosal defense system is stratified into pre-epithelial (alkaline mucus), epithelial (dynamic epithelial lining), and post-epithelial (microcirculation) components. The mucus lining the epithelial surface presents a diffusional barrier to ingested material (e.g., lipids) and also serves as an unstirred layer in which a pH gradient can be established to prevent acid-induced injury. The epithelial lining prevents entrance of any toxic material to the interstitium and, should it be damaged, it is rapidly resealed by migration of adjacent viable epithelial cells to cover the defect. Any acid or other material that has entered the interstitium is washed out by an intense neurogenic hyperemia. In general, the mucosal defense system is quite effective and any adverse gastrointestinal effects associated with the normal course of nutrient assimilation are minimal. However, there are two situations in which the mucosal defense system is known to be ineffective and result in gastric mucosal injury: inadvertent ingestion of H. pylori. or intentional ingestion of NSAIDs. H. pylori can penetrate the mucus layers and cause epithelial injury and inflammation, while at the same time preventing its clearance by the host immune system. NSAIDs weaken the mucus layer and cause epithelial cell injury.