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1、The Digestive System(also called the gastrointestinal or alimentary canal) 2021/5/251The primary functionsIngestionDigestionAbsorptionEliminationIntroductionAnatomically, the digestive system consist of a 30-foot long, mucous membrane-lined tube beginning with mouth and ending with the anus2021/5/25
2、2The digestive systemMouthPharynxEsophagusStomachSmall intestineLarge intestineLiverGallbladderPancreasAccessory organs of the digestive system2021/5/2532021/5/254The oral cavityThe teethThe tongueThe palateChewing and swallowingThe teeth are used to cut ,tear and crush food into smaller pieces. Eac
3、h tooth consists of pulp, cementum and enamel.The teeth are classified incisors , cuspids and molars.The tongue manipulates food in the mouth during mastication and deglutition.The palate the hard plate and the soft plate (the uvula hanging from the soft plate)2021/5/2552021/5/2562021/5/257The phary
4、nx or throat ,is a long muscular tube that serves as a passageway for food from the mouth to the esophagus and as a passway for air from nose to the windpipe.The esophagus is a long muscular tube extending from the pharynx to the stomach .Food is propelled by rhythmic contractions of muscles in the
5、wall of the esophagus. This process is called peristalsis.2021/5/258The stomach It is composed of an upper portion called fundus,a middle section known as the body and a lower portion, called the antrum. The cardiac sphincter relaxes and contracts to move food from the esophagus into the stomach ,wh
6、ereas the pyloric sphincter allows food to leave the stomach when it sufficiently digested. As the stomach fills ,the rugae unfolded, exposing the digestive glands and stimulating them to secret digestive enzymes and hydrochloric acid. These substances help transform food present to a semifluid subs
7、tance.2021/5/2592021/5/2510The small intestine is the region of the gut where nearly all of the chemical digestion of the nutrition components of food take place.It divided into 3 sections:1)the duodenum 2)the jejunum 3)the ileum In the wall of the entire small intestine are millions of villi. It is
8、 through the capillaries in the villi that completely digested nutrients pass into the bloodstream and lymph vessels. 2021/5/2511The large intestine is divided into 4 parts :cecum, colon,sigmoid colon,and rectum.The cecum is connected to the small intestine by the ileocecal valve.The colon has 3 div
9、isions : the ascending colon, the transverse colon, the sigmoid colon. As fluid waste from the small intestine pass through various sections of the colon ,water is reabsorbed into body.The rectum serves as a reservoir for feces.2021/5/25122021/5/2513The liver:located in the upper right quadrant of a
10、bdomen,produces bile.Besides producing bile,it has several other vital functions.It manufactures blood proteins,destorys old erythrocytes and releases bilirubin,removes poisons(detoxification） from the blood,stores and releases glycogen needed by the body.2021/5/25142021/5/2515The gallbladder：a pear
11、-shaped sac behind the lower portion of the liver,stores bile,which is continuously secreted by the hepatic cells between meals.2021/5/25162021/5/2517The pancreas:behind the stomach,manufactures digestive juice containing enzyme(amylase and lipase)that aid in the digestion of proteins,starches and fats.It also secretes insulin and glucagon.2021/5/25182021/5/2519Made by 1062021/5/2520部分资料从网络收集整理而来，供大家参考，感谢您的关注！
