Lect2 Digestion

Lect2 Digestion - 9/1/10 Lecture 2: Diges2on Read...

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Unformatted text preview: 9/1/10 Lecture 2: Diges2on Read Chapter 3, do 20 homework ques2ons, look at review ques2ons BRAIN EATING Hormonal Signals Mouth Esophagus Stomach Small intes2ne Large intes2ne Liver Pancreas Gall Bladder Gut Bacteria Neural Signals •  •  •  •  Digest food, absorb nutrients Absorb fluids Barrier and immune defense Produc2on of hormones and neurotransmiQers 1 9/1/10 Mechanical: teeth for bi2ng, tearing, crushing, grinding Saliva : water, electrolytes, mucus, enzymes •  Secre2on: under control of autonomic nervous system, both volume & type •  Type: composi2on depends on diet, »  Mediated by taste receptors Func*ons of Saliva: 1. lubrica2on & binding (mucus) 2. solubilizes dry food (for taste) 3. oral hygiene lysozyme: kills bacteria, prevents “dragon breath” 4. starts starch diges2on: salivary amylase Chaudhari, N & Roper SD. The cell biology of taste. J Cell Biol. 2010 190:285 ­96. •  Muscular •  Resistant to rough & abrasive foodstuff How would you test this? 2 9/1/10 Gastroesophageal reflux disease (GERD) –  acid from stomach refluxes back into the esophagus at the esophageal sphincter •  •  •  •  •  •  •  •  Ea2ng large por2ons of foods Lying down acer ea2ng Certain foods can be triggers Smoking/Alcohol Overweight Tight ­fifng clothes Gesta2onal hormonal changes Enlarged uterus during pregnancy Func2ons: 1.  Short term storage reservoir 2.  Chemical & enzyma2c diges2on 3.  Liquefac2on of food 4.  Slow release into small intes2ne** •  Food is crushed, ground, mixed into chyme, •  Small squirts of chyme then delivered to small intes2ne. •  Pyloric Sphincter: junc2on of stomach with intes2ne Rate influenced by 1.  Volume: stomach becomes distended 2.  Composi2on: Fat, protein, CHO Solid/liquid Gastric bypass 3 9/1/10 •  Func2on: –  Absorb water and electrolytes (Na, Cl, K) –  Forma2on and storage of feces –  Microbial fermenta2on: depends greatly on species •  Humans: short chain faQy acids important for health of intes2ne –  200 ­2000 ml/day of gas: •  99% is N2, O2, CO2 ,H2, methane –  Consump2on of indiges2ble carbohydrates (beans) causes increased fermenta2on and gas. •  Rectum and Anus Sa2ety Chyme Lumen Villi Mucosa Microvilli Esophageal sphincter Lacteal Pyloric sphincter Transit 2me Electrolyte Lysozyme Peristalsis Amylase Gastroesophageal reflux 4 ...
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This document was uploaded on 02/05/2011.

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