The digestive ducts include the oral cavity, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, ileum) and large intestine (cecum, colon, rectum, anal canal). There are two types of digestive glands: small digestive glands and large digestive glands. The small digestive glands are scattered in the walls of each part of the digestive duct, while the large digestive glands include three pairs of salivary glands (parotid, submandibular, and sublingual), liver, and pancreas, all of which discharge secretions into the digestive duct through ducts. First, the oral cavity (oral cavity) is formed on the basis of the bony oral cavity, the front opening is called the oral fissure, surrounded by the upper and lower lips; the back to the pharyngeal isthmus and pharyngeal traffic; the upper wall (top) is the palate; the lower wall is the floor of the mouth; both walls are called the cheeks. The entire oral cavity is separated by the upper and lower dental arches (including the alveolar process, gums and teeth) into two parts: the anterior part is called the oral vestibule, and the posterior part is called the intrinsic oral cavity. There are teeth and tongue in the oral cavity, and three pairs of salivary glands open on the surface of the oral mucosa. Second, the pharynx (pharynx) is a funnel-shaped muscular tube that is wide at the top and narrow at the bottom, slightly flattened at the front and back, with the upper end attached to the base of the skull and the lower end of the flat cricoid cartilage arch (the plane of the lower edge of the 6th cervical cone) continuing in the esophagus, with a total length of about 12 cm. The posterior wall is flat and the anterior wall is incomplete, communicating with the nasal, oral and laryngeal cavities. It is divided into nasopharynx, oropharynx and laryngopharynx. The pharyngeal cavity is the common passage between the respiratory and digestive tracts. In the lateral wall of the nasopharynx, there is the pharyngeal opening of the eustachian tube, which is connected to the middle ear drum via the eustachian tube. The esophagus is a backward and forward compressed muscular tube, located in front of the spine, with the upper end in the plane of the lower edge of the 6th cervical vertebra (cricoid cartilage) and the pharynx, and the lower end in the cardia of the stomach, with a total length of about 25 cm. According to its journey can be divided into three segments: neck, thorax and abdomen. Fourth, the stomach (stomach) is the most expanded part of the digestive tube, the food mass sent by the esophagus is temporarily stored in the stomach for partial digestion, and then sent to the duodenum after a certain period of time, in addition to the endocrine function of the stomach. Most of it is located in the upper part of the abdomen in the left quadrant of the rib cage. The entrance at the upper end, which is continuous with the esophagus, is called the cardia, and the exit at the lower end, which is connected to the duodenum, is called the pylorus. The upper edge of the concave to the upper right is called the small curve of the stomach, the lower edge of the convex to the lower left is called the large curve of the stomach, the part above the plane of the cardia to the upper left is called the fundus, near the pylorus is called the pylorus; the part between the fundus and the pylorus is called the body. V. Small intestine (small intestine) is the longest section of the digestive tube, adult length of about 5-7 meters. The upper end starts from the pylorus, and the lower end meets the large intestine in the right iliac fossa, which can be divided into three parts: duodenum, jejunum and ileum. The small intestine is the main part of food digestion and absorption. The large intestine is the last section of the digestive tube, about 1.5 meters long, starting from the right iliac fossa and ending at the anus, and can be divided into three sections: cecum, colon and rectum. The main function of the large intestine is to absorb water and excrete the undigested residue in the form of feces. The liver is the largest gland in the human body, weighing about 1.5 kg in adults, and is located in the right quarter and upper abdomen. The liver is enlarged above, facing the diaphragm, and is divided into two lobes, the right lobe is large and thick, and the left lobe is small and thin, by the sickle-shaped ligament. The underside of the liver faces downward to the left and is also called the dirty side. In the center of the dirty side, there is a transverse fissure called the hepatic portal, which is the gateway for the hepatic ducts, hepatic arteries, portal veins, lymphatic vessels and nerves to enter and exit the liver. The extrahepatic biliary tract includes the left and right hepatic ducts, the common hepatic duct, the cystic duct, the gallbladder and the common bile duct. The liver has the functions of bile secretion, glycogen storage, detoxification and phagocytosis defense, etc. In the embryonic period, there are also hematopoietic functions. The pancreas is the second largest gland in the body, spanning the front of the 1st and 2nd lumbar vertebrae, and can be divided into three parts: head, body and tail. The pancreas consists of two parts: the exocrine and endocrine parts. The glandular cells of the exocrine part secrete pancreatic juice, which flows into the pancreatic duct through the ducts at all levels, and the pancreatic duct opens into the duodenum together with the common bile duct. Pancreatic juice contains a variety of digestive enzymes, which play an important role in digesting food. The endocrine part refers to the islets, a group of cells scattered between the exocrine parts, which secrete hormones that enter the blood and lymph directly and are mainly involved in the regulation of glucose metabolism.