SI Session Digestive system Spring 2010 For Dr. Wright’s Bio 6 Class Designed by Pyeongsug Kim ©2010 Picture from

What are the organs of the digestive system and what do they do? What are some of the enzymes of the digestve system; where are they synthesized; where in the digestive system do they actually function, and what food molecules do they break down? What substances are secreted by what cells in the stomach? What food molecules are absorbed by the stomach? Where in the small intestine do digestion and absorption take place? What structures in the small intestine facilitate absorption? What happens in the large intestine? Why are there bacteria in the large intestine and what do they do? Liver function: what is the purpose of, and how, does the liver Produce and secrete bile? Detoxify blood (what does it remove from the blood) Store and release food molecules Make plasma proteins (what are they and what do they do) What is the purpose of the gall bladder? What is in pancreatic juice and what does it do? What cells in the pancreas are exocrine cells? What stimulates the secretion of pancreatic juice? What “arm” of the autonomic nervous system controls digestion?

Designed by Pyeongsug Kim, ©2008 Picture from: eating.htmlhttp:// eating.html Digestive system Responsible for…. -Food intake -Breaking eaten food down into its monomer molecules,  absorbing the monomer molecules into the body -Eliminate the undigested wastes from the body

Digestion -Hydrolysis of macromolecules (food molecules:carbohydrates, protein, fat, nucleic acid) into monomers : Glucose, amino acid, fatty acids…  ____________ -catalyzed by specific enzymes.  Digestive enzymes are made mostly by the pancreas and the small intestine. -absorbed through the intestinal mucosa  enter the blood or lymph. Designed by Pyeongsug Kim, ©2010 Picture from Catabolism *Only the monomers from the foods are allowed to pass into the bloodstream.

Designed by Pyeongsug Kim, ©2008 Oral cavity : Starch(a long chain) is hydrolyzed into shorter polysaccharide chains. Stomach : Significant digestion occurs but not fully digested to monomers. Small intestine : Most of the digestion and most of the absorption of water, monomers, and ions. Duodeum : Receives the acid chyme from stomach and digestive chemicals(enzymes) from all 3 accessay organs. Large intestine : The final water and ion absorption from the feces (Chyme after the small intestine) accurs Small intestine : Fat globules are emulsified by the detergent action of bile

Designed by Pyeongsug Kim, ©2008Mouth -___________(chewing) of food mixes it with saliva from salivary glands. -Enzyme: ______________ -A formation of a bolus of food Mastification Stomach -ingested food is churned; mixed with ____. -pepsinogen converted to pepsin  __________________ -Store food; initiate the digestion of protein -Forms and churns ______. -Rugae -Pylorus sphincter HCl Protein-digesting enzyme chyme Esophagus -Wavelike contraction: _________. -Esophageal sphincter Peristalsis Salivary amylase

Secretions of the stomach -mucosal surface forms gastric pits that lead into gastric glands. Mucus - goblet cells HCl - parietal cells Pepsinogen (pepsin)- chief cells Gastrin- G cells Entrochromaffin-like- histamine, serotonin Somatostatin- D cells Designed by Pyeongsug Kim, ©2010 Intrinsic factor ____________ - parietal cells (necessary for absorption of vitamin B12)

Designed by Pyeongsug Kim, ©2008 Small intestine -Absorption for carbo. Lipids, amino acids Ca2+… -to increase surface for absorption ______________ -Contraction peristalsis & ___________ -Enzymes Disaccharidase, peptidase, Phophtase -Most food molecules are absorbed in __________________ -Bile salts, water, electrolytes in _____. Micorvilli & villi segmentation Large intestine -Absorption for water, electrolyte, and minerals -Little or no digestion -_________________: produce Vit k and folic acid Bacteria (microflora) duodenum and jejunum ileum

Designed by Pyeongsug Kim, ©2008Liver -Largest internal organ -Functional unit: lobules -produces and secretes bile (via gall bladder) which facilitates digestion of fat. -Modifies the plasma concentrations of proteins, glucose, triglyceride, and ketone bodies. -Detoxifies the blood Chemical alternation Phagocytosis Production of urea or other less toxic molecules

Designed by Pyeongsug Kim, ©2008Liver(Cont’d) -Carbohydrates of metabolism glucose –>glycogen or glycogen  glucose glucogenesis~ produce glucose from amino acid or lactic acid -Lipid metabolism synthesis of triglycerides and cholesterol excretion of cholesterol in bile production of ketone bodies from fatty acids -Protein synthesis albumins, plasma transport proteins clotting factors(fibrinogens, prothrombin, etc)

Designed by Pyeongsug Kim, ©2008 Gall bladder -stores and concentrates bile -release to duodenum via common bile duct

Designed by Pyeongsug Kim, ©2008Pancreas -Secrete both exocrine(_____________) and endocrine(______________). Endocrine into the blood. Alpha cell – glucagon Beta cell - insulin Exocrine: _______________ into dudenum: trypsin, amylase, lipase Pancreatic juice Pancreatic isletPancreatic acini ↑ Blood glucose In Beta cell ↑insulin secretion In Beta cell ↑insulin secretion Cells uptake glucose Liver/muscle: Glucose  Glycogen Adipose tissue: Glucose  Triglyceride ↓Blood glucose Insulin ↓Blood glucose by stimulating… -cellular uptake of glucose -conversion of glucose to glycogen and fat

Pancreatic juice(exocrine) -Pancreatic acini -Contains water, bicarbonate, digestive enzyme Enzyme: trypsin(for protein), amylase(for starch), lipase(for triglycerides) -Activation trypsin  triggers activation of other pancreatic enzymes Designed by Pyeongsug Kim, ©2008 Secretin and CCK(cholecystokinin) - Duodenal hormones -Stimulate the secretion of pancreatic juice - Secretin ↑HCO3 production in pancreas; ↑HCO3 secretion into bile in liver secreted in response to below pH < 4.5 in duodenal  chyme is rapidly neutralized by alkaline pancreatic juice  ↓Secretin -CCK secreted in response to protein and fat of chyme in duodenum stimulates the production of pancretic enzymes: trypsin,amylase,lipase stimulates contraction of gall bladder to eject bile.

Designed by Pyeongsug Kim, ©2008 Picture from

Designed by Pyeongsug Kim, ©2008 Parasympathetic effect in digestive system -Mouse -Saliva secretion and thin -Stomach –increase secretion -Intestine – increase secretion -GI tract – stimulate motility -Pancreas – stimulate of exocrine secretions Table 9.4 in the 8 th ed. Picture from