The digestive system, which extends from the mouth to the anus, is responsible for receiving food, breaking it down into nutrients (a process called digestion), absorbing the nutrients into the bloodstream, and eliminating the indigestible parts of food from the body. The digestive tract consists of the mouth (see Biology of the Mouth), throat, esophagus, stomach, small intestine, large intestine, rectum, and anus. The digestive system also includes organs that lie outside the digestive tract: the pancreas, the liver, and the gallbladder.
Because the digestive system has a lot of reserve built into it, aging has relatively little effect on its function compared to its effects on other organ systems. Nonetheless, aging is a factor in several digestive system disorders. In particular, older adults are more likely to develop diverticulosis and to experience digestive tract disorders (for example, constipation) as a side effect of taking certain drugs.
