Salivary gland :
there are three pairs of salivary gland
1) Parotid gland - located below the opening of ear. The duct that transports saliva to the mouth is called the Stenson's duct. The mumps, caused by paramyxo virus , is an infection in Parotid gland.
2) Submaxillary/Submandibular gland - located between the upper & lower jaw. The duct that transports saliva to the mouth is called the Wharton's duct.
3) Sublingual gland - located below the tongue. The saliva is transported to the mouth by the duct of Rivinus.
These all gland produce saliva. Saliva is a fluid that contains 99% of water. It also contains Salivary amylase known as ptylin. The ptylin helps in the conversion of starch into maltose. It also contain lyzozymes that are anti-bacterial in nature.
Gastric glands :
there are three regions in the stomach that produces gastric juices.
1) Cardiac region - if contains mucus neck cells which produces mucus that keeps in the easy passage of food through the alimentary canal. It does not contain any enzyme.
2) Fundic region - it contains the types of cells. First, peptide cells/chief cells which produces pepsinogen (inactive form of pepsin; helps in the digestion of protein), prorennin (inactive form of rennin; helps in the digestion of caesin, the milk protein) & gastric lipase (that helps in the digestion of fats but due to acidic medium in stomach, it can not work properly). Second, parietal cells/oxyntic cells which produces HCl (helps in activating the inactive enzymes, pepsinogen and prorennin, into pepsin and rennin respectively; helps in killing bacteria; pH is about 1 to 2) & Castle's intrinsic factor (helps in the absorption of vitamin B12 ). Third, argentaffin cells which produces serotonin (a vasoconstrictor that constrict the vessels) & histamine (a vasodilator that relaxes the vessels).
3) Pyloric region - it produces mucus. It also contains gastrin cells/G-cells shock produces gastrin hormone which controls the motility of stomach and stimulates the section of gastric juices.
Liver:
It is the largest gland of the digestive system. It has high regenerative power. Liver has two lobes, the right lobe and the left lobe that are covered by a connective tissue called Glisson's capsule. Liver produces bile juice. It does not contain any enzyme. It contains by salts that help in the emulsification of fats. Large fat molecules are converted to smaller ones. Sodium glycocholate and sodium taurocholate are bile salts. bile also contains bile pigments, bilirubin and biliveridin. Liver is an important gland because it also synthesizes clotting factors, prothrombin and fibrinogen. In embryo blood cells are formed by liver.
Gall bladder:
It stores the bile juice. It helps in concentrating the bile juice as the bile juice from the liver is full of H2O so the walls of gall bladder sucks water. The duct from the right lobe and the left lobe combines to form bile duct. The gall bladder secretes the concentrated bile juice into the bile duct via cystic duct. This is together called common bile duct.
Pancreas:
The pancreas has two part, exocrine and endocrine. . The exocrine part is called Acinar cell. It produces trypsinogen, chemotrypsinogen, procarboxypeptidase, pancreatic amylase, pancreatic lipase and nuclease. The endocrine part is called the islets of langerhans. It produces hormones mainly insulin and glucagon. Insulin converts glucose into glycogen and it is produced by The Beta cells. Glucagon converts glycogen into glucose and is produced by the Alpha cells of pancreas. Pancreas has two ducts, the duct of Wirsung and the duct of Santorini.
Intestinal glands:
it is divided into two parts, the crypts of lieberkhun and the brunner's gland. The crypts of lieberkhun contains enterocytes that produces mucus, water and enzymes. These enzymes include sucrase, lactose, maltase, nucleotidase and nucleosidase. It also contains paneth cells that produces lyzozymes. Goblet cells are also present that produces mucus. Argentaffin cells produce histamine (vasodilator) and secritin (hormone that controls the secreation of all the enzymes of intestine). The Brunner's gland produces enzyme. It is present in the submucosa of duodenum.
Hepato-pancreatic duct:
the common bile duct from the liver combines with the common pancreatic duct to form hepato-pancreatic duct. This jointly opens into the duodenum. The opening of the common hepatic duct into the pancreatic duct is guarded by a sphincter called the sphincter of boyden. The opening of the hepato pancreatic duct into the duodenum is guarded by a sphincter called the sphincter of oddi. The ampulla of Vater is also present just above the sphincter of oddi.
