Question

Names of different digestive juices secreted in different organs of human digestive system and thier role in digestion

Answer 1

Digestive glands :. Salivary glands are three pairs: parotid, sublingual and submaxillary or submandibular, They secrete saliva containing watet salts mucin and an enzyme salivary amylase. Its pH is nearly neutral being 6.7 . Gastric glands :are simple branched and tubulat Types of cels present in the epithelium of the gastric glands are: Peptic cells (-Chief or Zymogenic or Zymogen cels) are usually basal in location and seaete gastric digestive enzymes as proenzymes pepsinogen and prorennin, They also produce small amount of gastric amylase and gastric lipase. Prorennin is secreted in young mammals It is not secreted in adult mammals - Oyntic cells ( Parietal cells) are the most numerous cels on the side walls of the gastric glands They are caled parietal cells as they lie against the basement membrane. They secrete hydrochloric acid (HCI) and Castle's intrinsic factor Mucous cells (Goblet cells) are present between other types of ceils and secrete mucus. Mucus isa lycoprotein and helps to neutralize the acid in stomach and protects stomach wall against HCI action and protein digestive enzymes The gastric glands also have two less common types of cels Argentaffin cells that are generlly located at the base of the glands and secrete serotonin, a potent vasoconstrictor Gastrin cells which occur in the pyloric antrum and produce gastrin. The latter stimulates gastric glands to release the gastric juice. Liver is the largest gland in the body,The liver consists of two lobes:left lobe and right lobe The structural and functional units of liver are the hepatic lobules containing hepatic cell's, Each lobule is covered by a thin connective tsue sheath called the Glisson's capsule. The bile secreted by the hepatic cells passes through the hepatic ducts andistored and concentrated In the gall ladder. The duct of gall bladder (ystic duct) long with the hepatic duct as the cormon hepato-pancreatic duct which is guarded by a sphincter called the sphincter of Oddi. rom the liver forms the common bile duct.The bile duct and the pancreatic duct open together intothe duodenum le contains ble salts,bilepigments (mainl biliribin sentialy the non io par of the haemoglobin), cholesterol. and phospholipids. Bile salts(sodium bicarbonate, sodium glycocholate, and sodium taurocholate) helpin the digestion of fats in the small intestine by bringing about their emulsification (conversion of large fat droplets nto small ones) and the rest are just being excreted. Bile salts are absorbed in the ileum. > The pancreas is a heterocrine gland partly exocrine and partly endocrine. The exocrine part of the pancreas consists of rounded lobules (adini) that secrete an alkaline pancreatic juice with pH 84. Pancreatic juice is poured into the duodenum. The pancreatic juice contains sodium bicarbonate three proenzymes; trypsinogen (activated to trypsin by enterokinase), chymotrypsinogen and procarboxypeptidase and some enzymes such as pancreatic amylase DNase, RNase and pancreatic lipase. The pancreatic juice helps in the digestion of starch, proteins, nucleic acids and fats therefore pancreaticjuice is also called complete digestive juice.The endocrine part of the pancreas consists of groups of islets of Langerhans. Each of it consists of three types of cells: alpha cells (secrete hormone glucagon), beta cells (secrete hormone insulin) and delta cells (secrete Intestinal glands lie in the wall of small intestine. They are of 2 types: secrete enzymes and mucus. They have two types of cells . hormone somatostatin) 0 The crypts of Lieberkuhn are simple tubular glands and occur throughout the small intestine between the villi. They Paneth cells are found in the bottom and are rich in zinc. They secrete lysozyme (antibacterial substance). Argentaffin cells, also known as enterochromaffin cells are located among epithelial cells. They produce serotonin which plays a role in stimulating peristaltic activity of the intestine () The Brunner's glands are branched tubular glands and are confined to the duodenum.They secrete alkaline watery fluid, a little enzyme and mucus. They open into the crypts of Lieberkuhn. The mixture of secretions of intestinal glands is called intestinal juice, or succus entericus (pH 7-8) Intestinal juice contains many enzymes, eg,amino-peptidases, dipeptidases, intestinal amylase, maltase,isomaltase,limt dextrinase,sucrase,lactase, intestinal lipase, nucleotidases or nucleophosphatases, nucleosidases, and enteropeptidase enterokinase). These enzymes act on all types of food. Digestion and Abserption A table with summarised process of digestion and absorption is given on the next page. Assimilation of food The blood transports absorbed food materials to different body cells where food materials become integral component.