Physiology of gastric emptying and pathophysiology of gastroparesis.

Current knowledge of the physiology of gastric emptying implicates a reservoir function for the gastric fundus, grinding and propulsive functions for the antrum, and the concept of the pylorus and duodenum as resistances to gastroduodenal flow. Although these areas differ markedly in their behavior, their contractile activities are coordinated in such a way that the delivery of nutrients to the small intestine occurs in an orderly and controlled manner. In this article we describe the functions of the gastric fundus, antrum, pylorus, and duodenum and how the contractile activities of these regions regulate gastric emptying, according to the composition of the meal and the physiologic and emotional state of the person. In addition we discuss the nature and possible mechanisms of the motor disturbances associated with abnormally slow gastric emptying.