Digestive System

When considering the potential toxic activity of various agents on the gastrointestinal (GI) tract, a number of mechanisms are possible. For example, acute toxic effects may result from direct irritants (e.g., strong acids and bases), whereas chronic effects maybe manifested as increased muscular layer thickness from bulking agents. Delayed effects maybe expressed years after exposure to the initial ulcerogenic or carcinogenic agents. In addition to an array of tissue responses, the mechanistic relationships between functional abnormalities and morphological alterations can be complex. The focus of this chapter is to examine structural and functional components of the GI tract that are important in understanding mechanisms involved in the toxicologic pathology of this organ system. A major part of the chapter stresses basic mechanisms of toxicologic damage, and how the GI tract responds to toxicologic insult. Also discussed in brief are morphologic approaches that can be used to study selected pathologic mechanisms of toxicological significance.