Lecture 7 - Nutrition and the digestion system

Stored as glycogen or fats 53 regulaon of digeson

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Unformatted text preview: in 4 in the US suffer –  Caused by stomach acid rising into esophagus –  Many contribu,ng factors 45 Vertebrates gastrointes,nal system  ­ Stomach •  Heartburn –  Tums •  Antacid made of sucrose and calcium carbonate (CaCO3) –  Prilosec Proton pump inhibitor 46 Vertebrates gastrointes,nal system – Small intes,ne •  Small intes,ne –  Diges,on of carbohydrates and proteins con,nues and the diges,on of fats and absorp,on of nutrients begins –  Nearly all diges,on of food, and absorp,on of food and water –  Hydroly,c enzymes found on luminal surface or secreted by pancreas into lumen –  Products of diges,on absorbed across epithelial cells and enter blood 47 Vertebrates gastrointes,nal system – Small intes,ne •  Small intes,ne –  Duodenum •  Most diges,on occurs –  Jejunum and ileum carry out 90% of the absorp,on of nutrients 48 Vertebrates gastrointes,nal system – Small intes,ne •  Specialized for increased surface area –  Increases surface area 600 ­fold –  Mucosa is folded –  Villi: finger ­like projec,ons –  Epithelial cells covered with microvilli crea,ng brush border •  Increases likelihood of encountering diges,ve enzyme and being absorbed 49 Vertebrates gastrointes,nal system – Small intes,ne •  Diges,on of carbohydrates and proteins: –  Produc,on of pep,dases •  Cleave small pep,des into absorbable amino acids –  Produc,on of maltase, lactase and sucrase •  Cleave common disaccharides into absorbable monosaccharaides •  Many humans stop producing lactose in childhood –  Lactose is cleaved and absorbed un,l bacteria digests it in the large intes,ne causing gas, abdominal pain and diarrhea 50 Vertebrates gastrointes,nal system – Small intes,ne •  Absorp,on of nutrients –  Diffusion, facilitated diffusion, osmosis, ac,ve transport and co ­ transport •  Vitamins, minerals, and water –  Do not require diges,on –  Absorbed in complete form –  Fat ­soluble vitamins follow pathway for fat absorp,on –  Small amounts of water...
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This document was uploaded on 03/05/2014.

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