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Chyme (; from Greek χυμός ''khymos'', "juice"〔(Chyme ), Online Etymology Dictionary〕〔(χυμός ), Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus Digital Library〕) is the semifluid mass of partly digested food that is expelled by the stomach into the duodenum and moves through the intestines during digestion.〔(chyme ), ''Merriam-Webster Online Dictionary''〕 Also known as "chymus", it is the liquid substance found in the stomach before passing through the pyloric valve and entering the duodenum. It results from the mechanical and chemical breakdown of a bolus and consists of partially digested food, water, hydrochloric acid, and various digestive enzymes. Chyme slowly passes through the pyloric sphincter and into the duodenum, where the extraction of nutrients begins. Depending on the quantity and contents of the meal, the stomach will digest the food into chyme in anywhere between 40 minutes to a few hours. With a pH of approximately 2, chyme emerging from the stomach is very acidic. The duodenum secretes a hormone, cholecystokinin (CCK), which causes the gall bladder to contract, releasing alkaline bile into the duodenum. CCK also causes the release of digestive enzymes from the pancreas. The duodenum is a short section of the small intestine located between the stomach and the rest of the small intestine. The duodenum also produces the hormone secretin to stimulate the pancreatic secretion of large amounts of sodium bicarbonate, which then raises pH of the chyme to 7 before it reaches the jejunum. The duodenum is protected by a thick layer of mucus and the neutralizing actions of the sodium bicarbonate and bile; therefore, the duodenum is not so sensitive to highly acidic chyme as the rest of the small intestine into which the chyme will proceed. At a pH of 7, the enzymes that were present from the stomach are no longer active. This then leads into the further breakdown of the nutrients still present by anaerobic bacteria, which at the same time help to package the remains. These bacteria also help synthesize vitamin B and vitamin K, which will be absorbed along with other nutrients. ==Properties== Chyme has a low pH that is countered by the production of bile, helping to further digest food. Chyme is part liquid and part solid: a thick semifluid mass of partially digested food and digestive secretions that is formed in the stomach and small intestine during digestion. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Chyme」の詳細全文を読む スポンサード リンク
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