Veterinary Biochemistry Lecture 3: Nutrition 2 PDF

VETM 1503:VETERINARY BIOCHEMISTRY LECTURE # 3: NUTRITION 2 Dr. Kavita R. Lall, B.Sc. (Hons.), D.V.M. (Hons.), M.Sc. (Dist.) OUTLINE  Learning objectives  Digestion and absorption LEARNING OBJECTIVES  Understand the basic concepts of digestion and...

VETM 1503:VETERINARY BIOCHEMISTRY LECTURE # 3: NUTRITION 2 Dr. Kavita R. Lall, B.Sc. (Hons.), D.V.M. (Hons.), M.Sc. (Dist.) OUTLINE  Learning objectives  Digestion and absorption LEARNING OBJECTIVES  Understand the basic concepts of digestion and absorption (macronutrients) in monogastrics and ruminants DIGESTION AND ABSORPTION  Digestion: Larger food particles are broken down into smaller particles  Mechanical  Chemical  Enzymatic  Absorption: Digested food crosses into the bloodstream, through the intestinal wall DIGESTION AND ABSORPTION CONT’D  Major events in digestion and absorption: 1. Mechanical homogenization and mixing of food with saliva and GIT fluids 2. Secretion of enzymes for hydrolysis of food molecules 3. Secretion of electrolytes, acid or base to provide an optimum environment for enzymatic digestion 4. Secretion of bile acids/salts for digestion and absorption of lipids 5. Transport of hydrolyzed food molecules across the intestinal epithelial cell into blood DIGESTION AND ABSORPTION CONT’D  Possible biochemical causes of digestive disorders: 1. Enzyme deficiency, e.g. lactase and sucrase 2. Malabsorption, e.g. of glucose and galactose as a result of defects in the Na+-glucose cotransporter (SGLT 1) 3. Absorption of unhydrolyzed polypeptides leading to immune responses, e.g. Celiac disease 4. Precipitation of cholesterol from bile as gallstones MONOGASTRIC CARBOHYDRATE DIGESTION MONOGASTRIC CARBOHYDRATE ABSORPTION RUMINANT CARBOHYDRATE DIGESTION AND ABSORPTION MONOGASTRIC PROTEIN DIGESTION MONOGASTRIC PROTEIN ABSORPTION RUMINANT PROTEIN DIGESTION AND ABSORPTION MONOGASTRIC LIPID DIGESTION  Stomach - churn and mix dietary lipids and to initiate enzymatic digestion; the lipid droplets are emulsified (kept apart) by dietary proteins (bile acids, the primary emulsifying agents in the small intestine, are not present in the gastric contents.)  Lingual and gastric lipases initiate lipid digestion by hydrolyzing triglycerides into glycerol and free fatty acids  Chyme empties slowly into the small intestine, allowing adequate time for pancreatic enzymes to digest lipids MONOGASTRIC LIPID ABSORPTION RUMINANT LIPID DIGESTION AND ABSORPTION THE END