A Focused Overview of Gastrointestinal Physiology

Abstract

The digestive system has a complex set of control mechanisms and functional components involved in transport of food, absorption of nutrients, and excretion of wastes. This review emphasizes the motor and secretory aspects of normal physiology since these functions have recognized responses to stimuli such as feeding and stress. Physiologic controls fall into three major categories: cellular properties (e.g. properties of the muscle fibers), nervous system control (including nerves within the bowel wall), and humoral factors (local and circulating). The intramural neural network is present throughout the smooth muscle tubular gut. This network of excitatory and inhibitory neurons has multiple receptors and is responsible for much of the intrinsic control over gastrointestinal events, particularly its motor behavior. There is a rich supply of sensory nerves from the gut to the central nervous system so that central mechanisms can interact with and modulate gastrointestinal function.