1、1The Digestive System(also called the gastrointestinal or alimentary canal)2The primary functionsIngestionDigestionAbsorptionEliminationIntroductionAnatomically,the digestive system consist of a 30-foot long,mucous membrane-lined tube beginning with mouth and ending with the anus3The digestive syste
2、mMouthPharynxEsophagusStomachSmall intestineLarge intestineLiverGallbladderPancreasAccessory organs of the digestive system45The oral cavityThe teethThe tongueThe palateChewing and swallowingThe teeth are used to cut,tear and crush food into smaller pieces.Each tooth consists of pulp,cementum and en
3、amel.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)678 The pharynx or throat,is a long muscular tube that serves as a passageway for f
4、ood 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 wall of the esophagus.This process is called peristalsis.9The stomach It
5、 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,whereas the pyloric sphincter allows food to leave the stomach when it sufficiently dig
6、ested.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 substance.1011 The small intestine is the region of the gut where nearly all of the chemical
7、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 through the capillaries in the villi that completely digested nutrients pass into the bloodstream and lym
8、ph vessels.12The 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 divisions:the ascending colon,the transverse colon,the sigmoid colon.As fluid waste from the small intestine pass through
9、 various sections of the colon,water is reabsorbed into body.The rectum serves as a reservoir for feces.1314 The liver:located in the upper right quadrant of abdomen,produces bile.Besides producing bile,it has several other vital functions.It manufactures blood proteins,destorys old erythrocytes and
10、 releases bilirubin,removes poisons(detoxification）from the blood,stores and releases glycogen needed by the body.1516 The gallbladder：a pear-shaped sac behind the lower portion of the liver,stores bile,which is continuously secreted by the hepatic cells between meals.1718 The 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.1920Made by 106
