Bio 449 Lecture 29 – Digestive Physiology I Nov. 17, 2010 Introduction Components of food Overview of GI system Digestion and absorption Components General structure of the GI "tube" Function and control of the GI tract Physical breakdown of food Mouth Esophagus Stomach Terms to Know Triglyceride Gastrointestinal system Digestion Absorption Serosa Submucosa Mucosa Lumen Peristalisis Motility Mastication Parietal cells Chief cells Goblet cells Pepsin(-ogen) Gastrin Chyme Pyloric sphincter Terms to Know Carbohydrate Monosaccharide Disaccharide Polysaccharide Starch Glycogen Readings Lectures 29-30: Chapter 21

Components of food

Simple Carbohydrates Fig. 2-7 Glucose Fructose + Galactose Glucose (dextrose) Galactose* MONOSACCHARIDES Glucose Fructose + Galactose Sucrose (table sugar) Maltose Lactose DISACCHARIDES Fig. 2-7

Complex Carbohydrates Animals Plants Yeasts and bacteria POLYSACCHARIDES Chitin (invertebrates only) Glycogen Glucose molecules Cellulose Starch Dextran Fig. 2-7

Lipids + Fig. 2-8 Fatty acid Glycerol MONOGLYCERIDE DIGLYCERIDE TRIGLYCERIDE + G L Y C E R O Oleic acid, a monounsaturated fatty acid Linolenic acid, a polyunsaturated fatty acid Palmitic acid, a saturated fatty acid Fig. 2-8

Proteins

Overview of GI system

Digestion and absorption SECRETION DIGESTION ABSORPTION MOTILITY Lumen of digestive tract Wall Interstitial fluid Blood Food Fig. 21-2

Carbohydrate Digestion Fig. 21-14

Protein & Fat Digestion Fig. 21-14

Motility Fig. 21-5 Direction of movement Receiving segment Time zero Seconds later Contraction Bolus Bolus moves forward No net forward movement Fig. 21-5

Components of the GI system Oral cavity Salivary glands Esophagus Pancreas Stomach Small intestine Rectum Large intestine Gallbladder Liver Fig. 21-3

General structure of the GI tube Submucosal glands Serosa Submucosa Mucosa Circular muscle Longitudinal muscle Fig. 21-3

General structure of the GI tube Epithelium Lymph vessel Artery and vein Mucosa Submucosa Circular muscle Longitudinal muscle Serosa Muscularis externa Fig. 21-3

Rugae: Surface folding increases area Stomach anatomy Esophagus Antrum Pylorus Rugae: Surface folding increases area Fundus Diaphragm Body Fig. 21-3

Gastric motility

Rugae: Surface folding increases area Stomach anatomy Esophagus Antrum Pylorus Rugae: Surface folding increases area Fundus Diaphragm Body Fig. 21-3

Gastric glands Surface epithelial cells pit Goblet cells Chief cells Parietal cells