From time to time the waste is excreted through a valve called the anus. Bacteria, which inhabit the intestines, are not usually thought of as part of the system. But certain friendly bacteria help break down food. If these are lost for some reason, perhaps as a result of antibiotic treatment for a disease caused by different bacteria, digestion is impaired. Every part of the digestive system has a job to do, and damage to any one of the parts interferes to some degree with effective digestion.
Dental problems can interfere with chewing, for example.
The salivary glands can become infected, most often by the mumps virus, but sometimes by bacteria. The salivary glands rarely may develop small stones or a benign tumor. Stones or tumors can be removed easily by a physician. Benign tumors can also affect the tongue. The tongue and esophagus are also subject to cancerous tumors, which can spread rapidly if not removed or treated early.