The Gastrointestinal Barrier

The gastrointestinal mucosa forms a barrier between the body and a lumenal environment which not only contains nutrients, but is laden with potentially hostile microorganisms and toxins. The challenge is to allow efficient transport of nutrients across the epithelium while rigorously excluding passage of harmful molecules and organisms into the animal. The exclusionary properties of the gastric and intestinal mucosa are referred to as the "gastrointestinal barrier".