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Digestive System

Major structures involved. Digestive System. STRUCTURES. MAIN ORGANS Mouth Pharynx Esophagus Stomach Small Intestine DUODENUM JEJUNUM ILEUM Large Intestine/Colon ASCENDING COLON TRANSVERSE COLON DESCENDING COLON SIGMOID COLON RECTUM ANAL CANAL. ACCESSORY ORGANS TEETH & TONGUE

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Digestive System

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  1. Major structures involved Digestive System

  2. STRUCTURES • MAIN ORGANS • Mouth • Pharynx • Esophagus • Stomach • Small Intestine • DUODENUM • JEJUNUM • ILEUM • Large Intestine/Colon • ASCENDING COLON • TRANSVERSE COLON • DESCENDING COLON • SIGMOID COLON • RECTUM • ANAL CANAL • ACCESSORY ORGANS • TEETH & TONGUE • SALIVARY GLANDS • PAROTID • SUBMANDIBULAR • SUBLINGUAL • LIVER • GALLBLADDER • PANCREAS • APPENDIX

  3. Mouth/Oral Cavity • Chemical digestion of carbohydrates: • Salivary glands secrete salivary amylase • Mechanical digestion of food into a bolus: Teeth and tongue

  4. Deglutition

  5. Pharynx (and upper esophageal sphincter) • Passes food to esophagus • Upper Esophageal Sphincter • During swallowing • Upper esophageal sphincter opens • Allows food, liquids to pass • Reduces backflow of food, liquids from the esophagus into the pharynx.

  6. Esophagus and Lower esophageal sphincter • Esophagus: Muscular walls (longitudinal and circular) causesperistalsis • Cardiac/Lower Esophageal Sphincter- prevents backflow of acidic food contents

  7. Stomach and Pyloric Sphincter • Mechanical digestion of food into chyme: 3 layers of muscle (longitudinal, circular, oblique) • Chemical digestion of proteins • Pepsin • When empty, lining lies in folds called rugae • Peristalsis drives movement of materials

  8. Peristalsis in stomach

  9. Small Intestine: Duodenum, Jejunum, Ileum • Mech/Chem Digestion • Absorption of Nutrients • Circular folds: • Plicae (plica, s) • Folds covered with: • Villi(villus, s) • Fingerlike projections • Covered w/ microvilli • Nutrient absorption takes place in capillaries of villi • Plicae/Villi SA, which  nutrient absorption

  10. Absorption of nutrients in the SI: Villi & Microvilli

  11. Duodenum • Bile from liver/gallbladder emulsifies fat (breaks it into smaller droplets)—mech dig. • Lipase from pancreas released here Other pancreatic enzymes: Proteases (protein) Amylase (carbohydrates)

  12. Small Intestine, cont’d • Secrete intestinal enzymes: • Peptidases (peptides  amino acids) • Sucrase, lactase, maltase (disaccharides  monosacharides)

  13. Ileocecalvalve • Regulates flow of materials between ileum (SI) and cecum (LI) • Plicaeof the small intestine & large intestine, appendix

  14. Large Intestine (all these words!!!) • Cecum (and appendix) • Ascending colon • Transverse colon • Descending colon • Sigmoid colon • Rectum •  Anal Canal

  15. Large Intestine • Water Absorption/Stool Formation • Transit time • Too fast  diarrhea (too much water in stool) • Too slow constipation (too little water in stool) • Vitamins B & K Production • Result from bacteria feeding on undigested material

  16. Peritoneum • Visceral Peritoneum: surrounds digestive tract • Parietal Peritoneum: lines abdominal cavity • Extensions: • Greater Omentum: hangs down from lower edge of stomach/transverse colon over intestines (“lace apron”) • Mesentery: connects intestines/ anchors intestines to posterior abdominal wall

  17. Rectum • Stores feces prior to elimination • Anal sphincter regulates movement through anal canal • Under voluntary control • Learned during “potty training”

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