34.11: Digestive System Processes - Elimination
- Describe the process of elimination and problems that can occur
The final step in digestion is the elimination of undigested food content and waste products. After food passes through the small intestine, the undigested food material enters the colon, where most of the water is reabsorbed. Recall that the colon is also home to the microflora called “intestinal flora” that aid in the digestion process. The semi-solid waste is moved through the colon by peristaltic movements of the muscle and is stored in the rectum. As the rectum expands in response to storage of fecal matter, it triggers the neural signals required to set up the urge to eliminate. The solid waste is eliminated through the anus using peristaltic movements of the rectum.
Common Problems with Elimination
Diarrhea and constipation are some of the most common health concerns that affect digestion. Constipation is a condition where the feces are hardened because of excess water removal in the colon. In contrast, if not enough water is removed from the feces, it results in diarrhea. Many bacteria, including the ones that cause cholera, affect the proteins involved in water reabsorption in the colon and result in excessive diarrhea.
Emesis
Emesis, or vomiting, is elimination of food by forceful expulsion through the mouth. It is often in response to an irritant that affects the digestive tract, including, but not limited to, viruses, bacteria, emotions, trauma, and food poisoning. This forceful expulsion of the food is due to the strong contractions produced by the stomach muscles. The process of emesis is regulated by the medulla.
Contributions and Attributions
- OpenStax College, Biology. October 17, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44742/latest...ol11448/latest . License : CC BY: Attribution
- Medical Physiology/Gastrointestinal Physiology/Motility. Provided by : Wikibooks. Located at : en.wikibooks.org/wiki/Medical...%23Mastication . License : CC BY-SA: Attribution-ShareAlike
- Ingestion. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Ingestion . License : CC BY-SA: Attribution-ShareAlike
- OpenStax College, Digestive System Processes. November 24, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44742/latest/ . License : CC BY: Attribution
- mastication. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/mastication . License : CC BY-SA: Attribution-ShareAlike
- ingestion. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/ingestion . License : CC BY-SA: Attribution-ShareAlike
- bolus. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/bolus . License : CC BY-SA: Attribution-ShareAlike
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- Boundless. Provided by : Boundless Learning. Located at : www.boundless.com//biology/definition/lipase . License : CC BY-SA: Attribution-ShareAlike
- chylomicron. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/chylomicron . License : CC BY-SA: Attribution-ShareAlike
- amylase. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/amylase . License : CC BY-SA: Attribution-ShareAlike
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- OpenStax College, Biology. October 17, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44742/latest...ol11448/latest . License : CC BY: Attribution
- Boundless. Provided by : Boundless Learning. Located at : www.boundless.com//biology/de...n/constipation . License : CC BY-SA: Attribution-ShareAlike
- intestinal flora. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/intestinal+flora . License : CC BY-SA: Attribution-ShareAlike
- emesis. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/emesis . License : CC BY-SA: Attribution-ShareAlike
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- Gut flora. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Gut_flora . License : Public Domain: No Known Copyright
Key Points
- Water is reabsorbed in the colon after undigested food enters it from the small intestine.
- Waste is moved through the colon by peristaltic movements of the muscle and is stored in the rectum.
- The rectum expands in response to the storage of fecal matter; neural signals are triggered, and the waste is eliminated from the anus by peristaltic movements of the rectum.
- Constipation is a condition where the feces are hardened because of excess water removal in the colon.
- Diarrhea results when large amounts of water are not removed from the feces.
- Emesis, or vomiting, is elimination of food by forceful expulsion through the mouth caused by the strong contractions produced by the stomach muscles.
Key Terms
- emesis : the act or process of vomiting
- intestinal flora : the bacterial colonies that normally live in the digestive tract of animals
- constipation : condition where the feces are hardened because of excess water removal in the colon