The food that you eat travels an amazing path, covering about 30 feet from intake to output. The journey takes anywhere from 20 hours to a few days.
The digestive system comprises two groups of organs: the alimentary canal (the part that does the actual digesting) and the accessory digestive organs (the parts that help digestion take place, such as the pancreas or the liver).
The alimentary canal, more commonly known as the gastrointestinal, or GI, tract, is a long, hollow muscular tube, which extends from the mouth to the anus.
The muscular walls move food down the tract via a series of coordinated, wave-like contractions.
|Here's a look at the GI tract:|
|Organ||What It Does With Food||How Long Food Is There|
|Mouth||The teeth break food into smaller bits, which are formed into a soft ball, called a bolus, by the tongue. Saliva lubricates the food and begins chemical digestion.||Minutes or less|
|Pharynx, or throat||The pharynx pushes the bolus into the esophagus.||Seconds|
|Esophagus||The bolus is moved through the 10-inch esophagus by a series of coordinated, wave-like contractions. At the end of the short journey, the opening to the stomach relaxes and opens until the bolus of food passes, then closes again to prevent stomach contents from backing up.||One to six seconds for liquids; |
30 to 60 seconds for solids
|Stomach||The stomach muscles keep food in motion and churn it with gastric juices containing enzymes and hydrochloric acid, killing potentially harmful bacteria and microorganisms and continuing the breakdown of food into smaller and smaller pieces. The resulting material is now called chyme.||Four hours (longer if a meal includes fatty foods)|
|Small intestine||The duodenum (the first section of the small intestine) adds bile and pancreatic juice to the chyme, which helps the intestines digest and absorb nutrients from the food. Most digestion and absorption take place in the small intestine.||Food first spends four hours in the duodenum, then two hours in the rest of the small intestine|
|Large intestine||Sodium and other salts, and most importantly water, are absorbed here. Leftover waste material is slowly pushed through the colon by muscular contractions until it reaches the rectum. Stool is ultimately eliminated from the body during a bowel movement from the rectum.||14 hours|