The digestive tract, consisting of the oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine, has a normal microbiota that is important for health The constant movement of materials through the gastrointestinal canal, the protective layer of mucus, the normal microbiota, and the harsh chemical environment in the stomach and small intestine help to prevent…

Infections or microbial toxins in the oral cavity can cause tooth decay , periodontal disease , and various types of ulcers Infections and intoxications of the gastrointestinal tract can cause general symptoms such as nausea, vomiting, diarrhea, and fever.

Be able to describe the major anatomical features of the human digestive system; describe the normal microbiota of various regions in the human digestive system; explain how microorganisms overcome the defenses of the digestive tract to cause infection or intoxication.