13 Bio 104 Digestive System Lecture Outline: Digestive System Hole’s HAP [Chapters 17 & 18] General Characteristics of the Alimentary Canal A. Functions 1. Ingestion - 2. Mechanical digestion - 3. Chemical digestion - 4. Propulsion - 5. Absorption - 6. Defecation - B. Components of Digestive system 1. Alimentary canal (GI tract) - 2. Accessory organs - C. Alimentary canal wall 1. Mucosa a. - - b. c. 2. Submucosa - - 3. Muscular layer - - 14 Bio 104 Digestive System 4. Serosa - serous membrane - adventitia D. Movements of the Tube E. Innervation of the Tube Submucosal plexus Myenteric plexus Parasympathetic Sympathetic Mouth A. Functions B. Parts of the Mouth 1. Cheeks and lips - - 15 Bio 104 Digestive System 2. Tongue - - papillae: o filliform – o fungiform – o circumvallate - - lingual fenulum ankyloglossia 3. Palate Hard palate - Soft palate - Uvula 4. Tonsils - palatine - lingual - pharyngeal 5. Teeth Enamel – Dentin – Pulp cavity Dentition formula: 3 2 1 4 1 2 3 Molars Premolars Canines Incisors Secondary teeth 16 Bio 104 Digestive System 6. Salivary glands - 3 pairs: a. Parotid b. Submandibular c. Sublingual - secretions of the salivary glands: a. Parotid b. Submandibular c. Sublingual - Saliva a. Components . electrolytes, buffers, glucoproteins, enzymes, wastes . b. Functions . moistens . stimulates . initiates Pharynx A. Characteristics . 3 divisions: Nasopharynx Oropharynx Laryngopharynx 17 Bio 104 Digestive System B. Swallowing Mechanism . Soft palate, uvula, hyoid, larynx ___________ . Epiglottis ____________ and closes off top of trachea . Muscles: - longitudinal muscle - inferior constrictor muscles . Peristaltic waves C. Deglutition bolus = 1. Buccal 2. Pharyngeal 3. Esophageal Esophagus A. Function o o B. Anatomy Esophageal hiatus Upper esophageal sphincter Lower esophageal sphincter C. Histology Mucosa Submucosa Muscular layer Adventitia 18 Bio 104 Digestive System Stomach A. Functions 1. 2. 3. 4. B. Anatomy Features 4 regions: rugae: C. Gastric secretions 1. pepsinogen 2. pepsin 3. hydrochloric acid 4. mucus 5. intrinsic factor Gastric pits: Gastric glands: a) mucous cells b) chief cells c) parietal cells 19 Bio 104 Digestive System D. Phases and regulation of gastric secretions Phases 1. Cephalic 2. Gastric 3. Intestinal Regulation of gastric secretions 1. 2. 3. 4. E. Gastric Activities Gastric Absorption Mixing & emptying Chyme = Rate of emptying: Enterogastric reflex F. Hormones Gastrin – CCK (cholecystokinin) – Secretin – 20 Bio 104 Digestive System Accessory Organs: Pancreas, Liver, and Gallbladder Pancreas A. Structure: head – body - tail – pancreatic duct (Wirsung) hepatopancreatic ampulla hepatopancreatic sphincter B. Histology 1. Pancreatic acini - 2. Pancreatic islets (Langerhans) a) Alpha cells _________ BG levels b) Beta cells __________ BG levels C. Pancreatic Juice pancreatic amylase – pancreatic lipase – trypsin, chymotrypsin, and carboxypeptidase - nucleases – bicarbonate ions – D. Regulation of secretions 21 Bio 104 Digestive System Liver A. Anatomy Lobes – Ligaments – Hepatic lobules – Hepatic cells – Hepatic sinusoids Kupffer cells Central veins B. Bile ducts and bile Bile ducts: _____________ ____________ right & left _____________ ___________ hepatic duct Composition of Bile: water bile salts o o bile pigments cholesterol electrolytes C. Liver Functions 1) CHO 2) Lipid 3) Protein 4) Storage 5) Removal 6) Detoxification 7) Synthesis 22 Bio 104 Digestive System Gallbladder Regulation of bile release: Stores and concentrates bile - releases bile --> cystic duct - stimulated by CCK between meals: hepatopancreatic sphincter around duodenal ampulla closes after a meal: CCK is released gall bladder to contract relaxes hepatopancreatic sphincter Small Intestine A. Divisions: Duodenum, Jejunum, Ileum Duodenum - - Jejunum - - Ileum - - - B. Membranes 1. Peritoneum parietal visceral retroperitoneal 2. Mesentery 3. Omenta Lesser Omentum Greater Omentum 23 Bio 104 Digestive System C. Histology 1. Plicae circulares 2. Mucosa Intestinal villi – mucosa plicae villi epithelium brush border ---------------------------------------------------------------> (increases surface area 600 times) Each villus contains: a) b) 3. Submucosa 4. Muscular layer 5. Serosa D. Enzymes peptidase – sucrase, maltase, lactase lipase – breaks down _______ _____________ + __________ enterokinase – converts ___________ to ____________ E. Hormones CCK - - - Secretin - - 24 Bio 104 Digestive System F. Regulation of Intestinal Secretions G. Absorption in the Small Intestine monosaccharides electrolytes fatty acids and glycerol H. Movements in the S.I. • mixing movements • peristalsis – • segmentation – • overdistended wall triggers peristaltic rush resulting in __________ Large Intestine [cecum, ascending, transverse, descending, sigmoid colon; rectum, anus] A. Cecum ileocecal valve – vermiform appendix - vestigial part - - B. Anatomical features haustra - diverticula - taenia coli - epiploic appendages - ascending, transverse, descending, sigmoid colon 25 Bio 104 Digestive System C. Rectum - last 15 cm of GI tract - rectal columns - anus (anal orifice): terminal 2-3 cm - internal anal sphincter - external anal sphincter D. Large Intestine Wall Mucosa - lack of villi - lots of goblet cells - intestinal glands Submucosa Muscular Layer Serosa E. Functions of the Large Intestine -little or no digestive function -absorbs water and electrolytes -secretes mucus -houses intestinal flora -forms feces -carries out defecation G. Movements of L.I. H. Feces - water, electrolytes, mucus - bacteria Color: bile pigments altered by bacteria Odor - produced by bacterial compounds 26 Bio 104 Digestive System Digestion and Absorption A. CHO digestion B. Lipid Digestion C. Protein Digestion D. Water Absorption 27 Bio 104 Digestive System Life Span Changes Clinical Disorders 28 Bio 104 Digestive System .