Carbohydrates Digestion and Absorption Monosaccharides disaccharides oligosaccharides polysaccharides Know names what they are made of bonds and examples of each Monosaccharides o Glucose Most abundant Blood sugar o Fructose fruit and veggie o Galactose milk o Formed from condensation of 2 monosaccharides o Types Disaccharides Glucose glucose MALTOSE Glucose fructose SUCROSE Glucose Galactose LACTOSE Oligosaccharides o 3 10 monosacchrides o linked by a 1 4 or B 1 4 glycosidic bonds a 1 4 B 1 4 Most B 1 4 are not digestible o Ex Raffinose gal glu fru stachyose gal gal glu fru Polysaccharides o Starch Storage form of CHO in plants TYPES Amylose 15 20 Glucose linked by a 1 4 bonds Linear molecule Amylopectin 80 85 Glucose linked by a 1 4 long straight Branched chain molecules chain a 1 6 branches o Glycogen Storage form of CHO in animals Liver distributes to entire body Muscle stays inside muscle Highly branched Energy source Glycogenolysis o Fiber Nondigestible plant polysaccharide B 1 4 glycosidic linkages Dietary fiber found intact and intrinsic in plants Functional fiber isolated extracted or TYPES manufactured tract Insoluble decreases transit time moves through G I tract quickly Ex lignans cellulose hemicellulose Soluble increases transit time delays G I Helps with increase absorption and Stimulates production of good Ex pectins gums berrys Fermentation by bacteria in colon produces hydrogen methane gas CO2 blood glucose bacteria Anitcarcinogenic properties Negative correlation with mortality rates associated with heart disease Cholesterol absorption Fat absorption Postprandial insulin response influences plasma glucose BENEFITS Carbohydrate digestion what happens in the mouth in the small intestine Begins in Mouth Digests only a 1 4 bonds o Salivary glands produce salivary amylase o Amylose digestion o Branched starches o Action of salivary amylase is INCOMPLETE Due to a 1 6 bonds time spent in mouth Stomach Small Intestines o HCL inactivates salivary amylase o Pancreatic secretion Bicarbonate regulates pH Pancreatic amylase digests starches Located in microvilli o Brush border enzymes Sucrase sucrose glu fru Lactase lactose glu gal Maltase maltose glu glu Isomaltase destrins glu glu Understand what happens at the brush border and how monosaccharides are transported in and out of cells Mechanisms of Transport o Passive Diffusion No energy required Limited by concentration gradient Small molecules and solutes Needs carrier protein o Facilitated Diffusion Rate determined by Integral membrane protein Functions as a transport Concentration gradient Amount of carrier available Rapidity of solute carrier interaction Rapidity of conformation change of carrier Needs carrier protein Requires ATP pumping against gradient Na K pump sodium IN potassium OUT 3 sodium higher outside lower inside 2 Potassium lower outside higher inside o Active Transport Carbohydrate Absorption o Glucose Sodium dependant Transporter SGLT1 To maintain Na concentration gradient sodium must be pumped out of cell using Na K pump Glucose enters hepatic portal system Enterocyte capillaries portal system liver o Galactose 2 sodium molecules are needed to attach to glucose to transfer into cell Same as glucose Con be converted to glucose to meet needs of enterocyte o Fructose Glucose Transporters Facilitated diffusion GLUT 5 Some are converted to glucose in enterocyte Transport to liver then to other part of body enterocytes o GLUT 1 erythrocytes placenta o GLUT 2 movement across basolateral membrane of o GLUT3 brain o GLUT4 insulin stimulates uptake of glucose at o GLUT5 absorption of fructose at small intestines muscles adipocytes o GLUT6 spleen brain o GLUT7 unknown o GLUT9 10 liver o SGLT1 uptake of glucose and galactose of lumen What happens if we have an enzyme deficiency Know non digestible carbohydrates know examples why they are non digestible and what happens to them in the large intestine Glycolysis Purpose o Oxidation of glucose o Energy production Location CYTOSOL Glucose by itself cant do anything it needs to be changed into Hexokinase muscle and glucokinase liver are enzymes that High amount of g 6 p turns off hexokinase Types glucose 6 phosphate convert glucose to g 6 p Insulin turns on glucokinase o Anaerobic w out oxygen Glucose pyruvate lactate Energy production ATP Glucose g 6 p 1ATP F6P F 1 6 BisP 1 ATP 1 3 BPG 3 PG 2 ATP PEP Pyruvate 2 ATP G 3 P 1 3 BPG 2 NADH Pyruvate lactate 2 NADH NET ENERGY PRODUCTION 2 ATP NADH o Aerobic w oxygen Glucose pyruvate acetyl CoA Energy production ATP NADH Glucose g 6 p 1ATP F6P F 1 6 BisP 1 ATP 1 3 BPG 3 PG 2 ATP PEP Pyruvate 2 ATP G 3 P 1 3 BPG 2 NADH Pyruvate acetyl CoA 2 NADH o Pyruvate enters mitochondria o NADH enters ETC NET ENERGY PRODUCTION 14 ATP KREB CYCLE Purpose o Amphibolic pathway o CHO fats and proteins can all enter and be completely o Provides precursors for synthesis pathways oxidized in to CO2 H2O and energy Energy Location MITOCHONDRIAL MATRIX Products o CO2 exhaled by lungs o H2O o Energy GTP NADH FADH o Beginning with Acetyl CoA 12 ATP o Beginning with Pyruvate 15 ATP Kreb 6 2 2 Glycolysis 2 4 Energy molecule ATP NADH FADH GTP Total 2 10 x3 2 x2 2 ATP 2 30 4 2 38 SHUTTLE SYSTEMS Malate Aspartate Shuttle aminotransferase o Moves NADH into mitochondria ETC o Enzymes malate dehydrogenase aspartate o Step 1 Oxaloacetate NADH H Malate NAD o Step 2 Malate moves into matrix o Step 3 Malate NADH Oxaloacetate NADH H o Step 4 Oxaloacetate is converted to aspartate o Step 5 aspartate moves out of matrix o Step 6 aspartate converted to oxaloacetate o NADH yields 3 ATP o Active in liver kidney heart o NADH FADH o Enzymes cytosolic g 3 p dehydrogenase o Step 1 Dihydroxyacetone phosphate NADH g 3 p o Step 2 glycerol 3 phosphate moves into mitochondria o Step 3 g 3 p FAD FADH2 digydroxyacetone o FADH yields only 2 ATP o Active in muscle and brain HMP Hexose Monophosphate shunt mitochondrial g 3 p dehydrogenase NAD Glycerol 3 Phosphate Shuttle phosphate o Generate important intermediates not produced in other Pentose phosphate pathway Purpose pathways Location Cytosol Products o Pentose phosphate o NADPH Used for synthesis of nucleic acid Used for synthesis f fatty acids and cholesterol o Intense exercise clears lactate from the muscle Cori Cycle Purpose Gluconeogenesis Purpose o Synthesis of glucose from non carbohydrate sources Pyruvate Kreb intermediates Amino acids NOT from fats Location CYTOSOL liver sometimes kidneys Not just the reverse of
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