Digestion and Absorption of Macronutrients PDF

These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or Wo...

These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Digestion and Absorption of Macronutrients Aaron Marshall, Ph.D. Department of Medical Education Modification before Absorption Starch, Proteins, and Fats  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Session Objectives Describe the mechanisms of nutrient digestion which precede absorption for all nutrients discussed Compare and contrast carbohydrate and protein handling by the GI tract Compare and contrast the steps needed to process and absorb triglycerides versus fat- soluble vitamins Track the fate (location, metabolic conversions, etc) of a bile salt from the time of synthesis in the liver to the end of a meal. Describe the beneficial features, and challenges, of using micelles or chylomicrons as a tool to facilitate absorption  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. INTRO CONCEPTS FOR DIGESTION AND ABSORPTION -- SURFACE AREA AND SECRETIONS  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. A large surface of GI tract is necessary for absorption. (brush border membrane)  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Secretions [e.g. salivary and pancreatic] from various places are necessary for digestion and absorption  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Acinar/Ductal Structure is found in both salivary glands and pancreas Epithelial Cell Types 1. Ductal Cells - fluid Ductal secretion and ion cells modification 2. Acinar Cells- Mucous (viscous fluid) or Serous...... (fluid with soluble proteins)........ Acinar cells...  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Saliva prepares food for digestion 95% of saliva from 3 major salivary glands 5% from lingual (tongue) glands salt water proteins mucins  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Saliva proteins from parotid acini mucins lubrication Salivary -amylase Starch (carbohydrate) digestion destroyed in stomach acid Lingual lipase (tongue) and salivary lipase triglyceride (fat) digestion Lysozyme, secretory IgA, lactoferrin bacteria-static or -cidal Haptocorrin Vitamin B12 luminal chaperone  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to Zymogen - is an inactive precursor of an enzyme. University of Cincinnati, College of Medicine. Pancreas Exocrine = 85% mass (rest is endocrine organ) Secretes: NaHCO3 (sodium bicarbonate) to neutralize gastric acid Zymogens crucial for digestion  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Pancreatic Acinus acinar cells enzymes blood blood duct cells HCO3- secretin CCK Duodenum Duodenum & Jejunum Acidic acid amino acids chyme Lumen fatty acids  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to Duct Cell Diagram University of Cincinnati, College of Medicine. Note that ions are moving in opposite CO2 CO2 + H2O directions to that in parietal cells. carbonic anhydrase HCO3- H+ + HCO3- lumen CFTR HCO3- blood Cystic Fibrosis Transmembrane Regulator Cl- Na+ HCO3- Cl- H+ HCO3- Na+ basolateral apical These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine.  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Acid/Base Neutralization in the Gut Stomach H+ lumen HCO3- blood neutral neutral Intestine HCO3- lumen H+ blood Progression of chyme from stomach to intestine results in neutralization of pH in lumen and blood.  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Acid/Base with Vomiting Stomach H+ lumen Vomit-lose HCO3- blood contents of stomach Intestine HCO3- lumen H+ blood Vomiting can put a heavy alkaline load into the blood.  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. ENZYMATIC DIGESTION OF NUTRIENTS  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Chart of digestive enzymes Enteropeptidase Gastric lipase  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. COMPLEX CARBOHYDRATE DIGESTION  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Complex carbohydrate (starch) digestion -amylase secreted into gut lumen from -amylase parotid gland (minor) and pancreas (excess) Pancreatic enzyme secretion stimulated -amylase by cholecystokinin (CCK)  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Apical membrane hydrolases Membrane- associated enzymes (aka brush border enzymes) digest nutrients directly at the surface of the absorbing epithelial cells  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to Enterocyte surface digestion of University of Cincinnati, College of Medicine. CHO Enzymes on luminal (apical) reduce variety surface of small intestinal epithelium of molecules to absorb Starch Lactase deficiency Osmotic diarrhea X  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Lactose Intolerance Lactase glucose + galactose Lactose Increased luminal osmolality Net water accumulation in lumen Luminal distension Enhanced peristalsis Watery diarrhea  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Intestinal absorption of sugars 100% absorbed Glucose-Galactose Malabsorption by end of jejunum Osmotic diarrhea Na+ glucose (galactose) SGLT1X Na+ ~ K+ fructose GLUT 5 GLUT 2  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. PROTEIN DIGESTION  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Protein digestion: multi-organ involvement and zymogens Stomach HCl Pepsinogen Pepsin Duodenal epithelium Enteropeptidase + Trypsinogen (enterokinase) Trypsin Pancreas Chymotrypsinogen Chymotrypsin Proelastase Elastase Procarboxypeptidase A Carboxypeptidase A Procarboxypeptidase B Carboxypeptidase B  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Trypsinogen Proteases are packaged in the pancreas as inactive precursors Activation occurs in the small intestine  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Peptide and amino acid absorption Abundant surface digestion of peptides Dipeptides Difficult to digest to monomer form, and resulting set of amino acids highly Dipeptides varied  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Intestinal ammonia production gut bacteria protease urease NH3 Portal vein takes the intestinal NH3/NH4 to the liver for conversion to less toxic urea (Urea Cycle ala Dr. Lieberman) glutamine glutaminase Some circulating urea (not cleared by glutamate + NH kidney) permeates into bowel lumen and 3 sustains a futile detoxification cycle.  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to Epithelial transport of amino University of Cincinnati, College of Medicine. acids 100% absorbed by end of jejunum H+ dipeptides PEPT1 Na+ Na+ ~ K+ amino acids multiple amino multiple acids multiple  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. LIPID DIGESTION  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Dietary Fats supply 40% of daily Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. calories Ingest ~100gm/day 9 kcal/gm lipid 4 kcal/gm CHO 90-95% (aka. triglycerides)  These PPT slides are intended for private use for University of Cincinnati, College of Medicine students ONLY. Do NOT distribute or transmit them in any form by any mechanical, photographic or electronic process, including electronically or digitally on the Internet or World Wide Web or to any persons not matriculated to University of Cincinnati, College of Medicine. Fat soluble vitamins A,D,E,K Piggy back on absorption Fats: ~100 gm/day mechanisms of more abundant lipids OH Vitamin A (retinol)