Gastrointestinal Physiology and Pathophysiology

Rotaviruses, noroviruses, astroviruses, and enteric adenoviruses are the four major viral causes of acute gastroenteritis, which is a major public health concern and a common cause of morbidity worldwide and mortality in low income settings. Although the intestinal epithelium serves as a protective barrier, enteric viral pathogens disrupt normal intestinal homeostasis, resulting in excessive nutrient and water loss. However, the cellular and molecular mechanisms responsible for viral diarrhea are not fully understood. While significant advances in viral diarrheal disease research have been accomplished, most of our understanding of the pathogenesis of gastroenteritis has come from studies of bacterial pathogens. The goal of this chapter is to describe the current understanding of normal intestinal physiology and compare the molecular mechanisms that are altered in diarrheal diseases induced by bacterial or viral pathogens.