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CHAPTER 24- DigestionEnzymes Involved in DigestionSalivary amylaseoSecreted and Activein the mouthoSecreted by the Salivary glands(Parotid and Submandibular glands)oBreaks down Carbohydrates(Starch)oInactivein the stomachoConverts polysaccharides to disaccharidesPancreatic AmylaseoSecreted into the duodenum of the small intestineoSecreted by the PancreasoBreaks down glycogen and Carbohydrates(Starch) that have be broken-downoBreaks down into monosaccharidesLingual LipaseoSecreted into the mouth but inactiveoSecretedby the lingual glands in the tongueoActivatedin the stomach due to its acidityoBreaks down into small lipidsGastric LipaseoSecreted in the stomachoActivein the stomachoSecreted by chief cells oinactivein the duodenum of the small intestinePancreatic LipaseoSecreted into the duodenum of the small intestineoSecreted by the PancreasoBreaks down into fatty acids/monoglycerides through emulsification (bile salts)PepsinoSecreted by the Chief cells as Pepsinogen oPepsinogen comes in contact with the HCL turns into PepsinoTurns proteins into smaller peptide chains TrypsinoSecreted as trypsinogen (inactive)from the pancreasoBrush border enzymes(enterokinase) actives TrypsinoBreaks down protein into amino acidsChymotrypsinoSecreted as Chymotrypsinogen(inactive)by the pancreasoActivated by TrypsinoBreaks down amino acidsElastase
oSecreted proelastase (inactive)by the pancreasoActivated by the TrypsinoBreaks down into amino acidsCarboxypeptidaseoSecreted procarboxypeptidase (inactive)by the pancreas.oBreaks down into amino acidsBrush boarders oBreaks down Proteins and carbs amino acids and monosaccharides. oFound on the on the surface of the microvilliAbsorptionLipidsoShort ChainsSimple diffusion(to the liver)oLong chainsThe lipids are broken down and the monoglycerides and fatty acids(via bile salts)(micelles) are secreted into the interstitial fluid via exocytosisThey enter the lacteals and are carried through the blood streamMonosaccharidesoFructoseFacilitated diffusionoGlucose and GalactoseTransported via secondary active transport that is coupled to activeNaGlucose and two Na must be filled in order for transporter to occurGalactose and glucose compete for the transportProteinsoSome amino acids enter absorptive cells via Na+ dependent secondary active transportoSome amino acids can diffusionoDipeptides and Tripeptides use active transport with H+Electrolytes oNa+basolateral sodium-potassium pumps oCalcium ionsAbsorbed Actively stimulated by calcitrioloIron, potassium, magnesium, and phosphate ionsAbsorbed via active transportVitaminsoFat solubleingested lipids in micellesSimple DiffusionoWater soluble
Simple diffusionoB12Combined with intrinsic factorAbsorbed in the ileumActive transportWatero8.3 liters in SI