The Gastrointestinal Tract I Oral Cavity A mastication chewing breaks down food 1 increases surface area B Saliva 1 Enzymes 2 lysozymes II Esophagus A Muscular tube connects the back of the mouth and stomach 1 movement of food via peristalsis B Lower esophageal sphincter circular muscular valve 1 relaxes to let food into the stomach 8 19 2015 1 C GERD gastro esophageal reflux disease 1 relaxation of lower esophageal sphincter 2 stomach acid comes in contact with esophagus 3 possible causes a Spicy foods b Caffeine c Fatty foods d Pregnancy III Stomach A Holds food B Mechanical mixing and breaking down of food C Gastric secretions C Gastric Secretions 1 Gastrin a Release of HCL and pepsinogen 2 Hydrochloric acid HCL a Kills bacteria b Denatures proteins c Inactivates lingual lipase 3 Pepsinogen a Inactive precursor to pepsin 4 Mucus a Protects stomach lining b Contains bicarbonate 5 Intrinsic factor 8 19 2015 2 Pyloric Sphincter IV A Circular muscular valve separating stomach from duodenum B Regulates movement of food and acid from stomach to small intestine V Small Intestine A Three sections 1 Duodenum 2 Jejunum 3 Ileum B Lining 1 Folded into finger like projections called villi 2 villi are covered with microvilli 3 Micro villi brush border 4 Digestion of nutrients usually completed on 5 Enterocytes cells that line the villi brush border a villar tip cells b mid villar cells hormones c Crypt cells 1 Secrete digestive enzymes and 8 19 2015 3 1 digestion and absorption continues C Jejunum D Ileum 1 absorption VI Large intestine A smooth lining no villi B water and electrolyte absorption C intestinal microflora 1 bacterial breakdown of fiber D temporary storage and concentration until defecation VII Accessory organs A Pancreas 1 Acini secrete enzymes into GI tract 2 Islet tissue a secrete hormones into blood 1 beta 2 alpha 3 delta b not connected to GI 8 19 2015 4 B Liver 1 Makes bile a Emulsifier for fats required for fat digestion c Bile 1 made in hepatocytes from cholesterol 2 stored in gall bladder 2 Metabolizes drugs alcohol and other toxins 4 Makes plasma proteins a Transport proteins 1 albumin a major transport protein b Maintains osmotic pressure c 2 transferrin transports iron 3 lipoproteins a 5 types b Carry various lipid cholesterol components to tissues VIII Circulation of Nutrients A Vascular System carries nutrients in blood to liver and then disperses it to body B Lymph System exogenous lipid transport 8 19 2015 5 Carbohydrates Major source of energy fuel in the average Approximately of total caloric intake in diet form of I Chemical Structure A CH2O H H C O I Chemical Structure cont A Simple H C O H C OH H C OH H B Complex 1 II Monosaccahrides A Types 3 triose 4 tetrose 5 pentose 6 hexose 7 heptose 1 Hexose a Major source of energy source b Glucose fructose galactose 2 Pentose a Made from hexoses b Ribose B Dietary monosaccharides 1 Glucose a most abundant monosaccharide 2 2 Fructose 3 Galactose III Disaccharides A Formed from condensation of 2 monosaccharides B Types 1 glucose glucose 2 glucose fructose 3 glucose galactose C High Fructose Corn Syrup 1 50 glucose 50 fructose a cane sugar and beet sugar 2 45 glucose 55 fructose 3 IV Oligosaccharides A 3 10 monosaccharides 1 raffinose gal glu fruc 2 stachyose gal gal gluc fruc 3 found in beans peas and whole bran V Polysaccharides A Starch 1 Storage form of CHO in plants 2 Types a Amylose b Amylopectin B Glycogen 1 storage form of CHO in animals 2 highly branched 3 energy source 4 C Fiber 1 Non digestible plant polysaccharides 2 Defined by USDA a Dietary fiber b Functional fiber 3 Types a Insoluble b Soluble a Insoluble fiber 1 does not dissolve in water 2 decreases transit time 3 increases fecal bulk 4 ex lignans celluloses some hemicelluloses 1 dissolves in water 2 increases transit time 3 ex pectins gums some hemicelluloses b Soluble fiber 4 fermented by bacteria in colon a hydrogen methane gas CO2 short chain fatty 1 Short Chain fatty acids acids Acetic acid Butyric acid 2 Functions of short chain FAs a stimulate water and sodium absorption into mucosa b provide colonocytes with energy c enhanced immune function 5 5 Excreted as fecal matter carries bile with it 6 Sources fruits vegetables and whole grains Digestion of Carbohydrates I Begins in mouth A Salivary glands produce salivary amylase 1 digests 1 4 bonds 2 does not break down 1 6 bonds B Amylose digestion C Branched Starches 6 II Stomach A HCL inactivates salivary amylase III Small Intestine A Pancreatic secretions 1 bicarbonate B Brush border enzymes 1 sucrase 2 lactase 3 maltase Absorption and Transport 7 I Location A Small Intestine II Mechanisms of Transport A Passive Diffusion B Facilitated Diffusion C Active Transport A Passive Diffusion of solute through membrane 1 no energy required 2 3 small molecules and solutes B Facilitated Diffusion 1 needs a carrier protein a Integral membrane protein 2 rate determined by a Concentration gradient b Amount of carrier available 8 C Active Transport 1 needs a carrier protein 2 requires energy ATP 3 example Na K pump III Carbohydrate Absorption A Glucose 1 sodium dependent 2 transporter SGLT1 3 to maintain Na concentration gradient 4 glucose enters hepatic portal system B Galactose 1 same as glucose 2 C Fructose 1 facilitated diffusion GLUT 5 9 D Glucose Transporters 1 GLUT1 erythrocytes placenta 2 GLUT2 3 GLUT3 brain 4 GLUT4 5 GLUT5 6 GLUT6 spleen brain 7 GLUT7 unknown 8 GLUT9 10 liver 9 SGLT1 IV Transport A Portal Circulation Liver 1 Facilitated transport a Fructose b Galactose c Glucose 2 3 Glucose not taken up by liver a Facilitated insulin dependent b Facilitated insulin independent Metabolic Pathways of Carbohydrates 10 Glycolysis I Purpose A Oxidation of glucose B Energy production II Location A cytosol III Types A Anaerobic 1 without oxygen 2 glucose pyruvate lactate B Aerobic 1 With oxygen 2 glucose pyruvate acetyl CoA Glycolysis on overheads 11 Glucokinase A Functions in B Upregulated by insulin C Hexokinase A Functions B Downregulated by glucose 6 P C A Anaerobic Glycolysis 1 Energy production a ATP Glucose glucose 6 phosphate F6P F 1 6 BisP 1 3 BPG 3 PG PEP Pyruvate b NADH G 3 P 1 3 BPG Pyruvate lactate B Aerobic Glycolysis 1 Energy production a ATP Glucose glucose 6 phosphate F6P F 1 6 BisP 1 3 BPG 3 PG PEP Pyruvate b NADH G 3 P 1 3 BPG Pyruvate acetyl CoA 1 pyruvate enters mitochondria 2 NADH enters ETC 12 Lactate Acetyl CoA Krebs Cycle Glucose Pyruvate Glucose Pyruvate Pyruvate Acetyl CoA Krebs
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