Hormonal Control of Digestion
Hormone | Source | Target Organ | Action |
Gastrin | Pyloric stomach | Stomach | Stimulates gastric glands to secrete and release gastric juice. It also stimulates gastric mobility. |
Enterogastrone(=Gastric Inhibitory Peptide-GIP) | Duodenum | Stomach | Inhibits gastric secretion and mobility(slows gastric contraction). |
Secretin-first hormone discovered by scientists | Duodenum |
Pancreas Liver Stomach |
Release bicarbonates in the pancreatic juice. Increases secretion of bile. Decreases gastric secretion and mortality. |
Cholecystokinin-Pancreozymin(CCK-Pz) | Small Intestine | Gall bladder and pancreas | Contracts the gall bladder to release bile. Stimulates pancreas to secrete and release digestive enzymes in the pancreatic juice. |
Duocrinin | Duodenum | Duodenum | Stimulates the Brunner’s glands to release mucus and enzymes into the intestinal juice. |
Enterocrinin | Small Intestine | Small Intestine | Stimulates the crypts of Lieberkuhn to release enzymes into the intestinal juice. |
Vasoactive Intestinal Peptide(VIP) | Small Intestine | Small Intestine and stomach | Dilates peripheral blood vessels of the gut. Inhibits gastric acid secretion. |
Villikinin | Small Intestine | Small Intestine | Accelerates movements of villi. |
Somatostatin(SS) | Delta cells of islets of Langerhans of the Suppressespancreas. | Pancreas, Gastrointestinal tract | Suppresses the release of hormones from the digestive tract. |
Pancreatic Polypeptide(PP) | Pancreatic Polypeptide cells | Pancreas | Inhibits the release of pancreatic juice from the pancreas. |
Digestion Of Food
Food is a substance taken from outside that nourishes the body, builds tissues, and supplies energy. Essential components of our food are mainly carbohydrates, proteins, and fats. Vitamins and minerals are also needed in small quantities. Water plays a crucial role in metabolic processes and also prohibits dehydration of the body. Our body cannot utilize biomolecules in food in their original form hence they have to be converted into simple substances in the digestive system.
Digestion is known as the process of conversion of complex food substances into simple absorbable forms. The digestive system carries out the latter through mechanical and biochemical methods. Absorption is the process by which nutrients pass from the alimentary canal into blood and lymph through its mucosa. The absorbed food materials are carried by blood and lymph. The lymph is finally moved to the blood circulation. The blood transports absorbed food materials to different tissues where food materials are utilized for various activities like energy, growth, and repair. This process is called assimilation.
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